What is SEO – Search Engine Optimization?

Search Engine Optimization (SEO) explains to search engines about your website, making sure it connects with users by serving relevant and valuable results in line with their search queries.

When done right, SEO can help you rank on the first search engine results pages (SERPs) for the most relevant and valuable keywords determined by your target demographics, driving qualified traffic to your site.

SEO is a form of digital marketing that can be used for any website. It assists in boosting a site’s visibility on search engines such as Google and Microsoft Bing. Whether your site sells products or services or provides expert knowledge on a particular subject, SEO can ensure that the traffic comes from a relevant audience and, therefore, helps increase online visibility.

The more visible your pages are in search results, the more likely they will be found and visited.

This introductory guide will explain what SEO is and what it involves in 2025.

As technology evolves, so do websites, their structures, and the tools you use to reach search engines.

A web search could be voice-activated, a click could be a tap on a mobile phone screen, and information can be summarized by artificial intelligence (AI) before we see results from our search engine.

We will then cover all these various components of SEO and guide you to resources for your further studies.

How is SEO different from SEM and PPC?

In search marketing, it is essential to understand the differences between SEO, SEM, and PPC. With SEO, we look for organic search visibility, while SEM and PPC are paid methods.

In this guide, we’ll explain these terms, address their meanings, and outline how they apply to different facets of digital marketing.

SEO vs. SEM

You may have heard SEM referred to as search engine marketing — or, more accurately, search marketing.

Digital marketing includes any promotional activity that promotes a service or product online. It is an umbrella term for the performance of SEO and PPC (pay-per-click, e.g., Google Ads) activities that generate traffic through organic search and paid search channels.

How, then, do SEO and SEM differ? They aren’t different from each other technically – SEO is just one-half of SEM:

• SEO: Organic results clicks from search engines.
• SEM: This is driven by organic and paid results in the search engines.
• PPC: Clicks on paid results from the search engines.

Here is how to best think about SEM, SEO and PPC:

Imagine SEM is a coin. SEO is one side of that coin, and PPC is the flip side.

SEO vs. PPC

PPC (Pay-per-Click) is a type of digital marketing in which an advertiser is charged when one of their ads is clicked.

Keyword-based model: Advertisers bid on particular keywords or phrases for their ads to appear in search engine results.

When a user searches for any of these keywords or phrases, an advertiser’s ad (paid listing) will show among the top results.

So, once again, search marketing is like a coin, and SEO and PPC are two sides of that coin:

• With PPC, the advertiser pays for every time a search user clicks on their paid listing.
• With SEO, the search result listing is not paid for directly, even though SEO is sold as a service. Page and site optimization require time and investment, meaning organic search is not “free.”

There has been some debate about the value of either channel: “SEO vs. PPC” – which is more effective or has a better ROI. Nevertheless, SEO and PPC are complementary digital marketing channels. Ideally, you would always choose both (budget-allowing).

As previously noted, the industry often uses SEM and PPC synonymously. But that is not true here on Organic SEO IT.

Whenever we refer to “SEM,” we will mean both SEO (organic search) and PPC (paid search).

If you want the backstory on how “SEM” came to mean “PPC” instead of also including SEO, check out these articles:

• From PPC / Paid Search Into SEM, Because of Wikipedia.
• Do SEM = SEO + CPC Still Add Up?

Why is SEO important?

Looking forward, SEO will remain an important marketing channel.

• 53% of all website traffic comes from organic search, per a 2019 BrightEdge study.
• There are over 8.5 billion searches daily on Google Search, with Google holding 91% of the global search engine market.

No wonder that, with such a fantastic audience reach, the global SEO industry is projected to reach $122.11 billion by 2028.

SEO produces actual business results for brands, businesses, and organizations of any size. The action of searching or the search user interface, in whatever format (typed, voiced, or image query), has effectively become second nature for global internet users as the default means of accessing the information they seek among the ocean of billions of web pages (4.3 billion pages on the indexed web, as of September 2024).

The need to travel somewhere, the need to do something, to find out something, to research, to buy a product/service are all the things people search for, and their journey starts with a search.

However, the search is highly fragmented, especially regarding consumer-intent actions. Users can search on traditional web search engines such as (Google and Microsoft Bing), social platforms (such as YouTube and TikTok) or retailer websites (such as Amazon).

(Amazon was the starting point for product searches for 56% of U.S. online shoppers last year, versus 46% who began with a search engine such as Google.) Other things to know from that same research:

• 37% start on Walmart.
• 25% start on YouTube.
• 20% start on Facebook.
• 19% start on Instagram.
• 19% start on TikTok.

Another interesting aspect of this data (compared to previous years) is the growth in social sources, especially TikTok as a product search and knowledge search (how to do X search activity).

A 2023 study shows that a staggering 51% of Gen Z women would instead start a search on TikTok than anywhere else online for information.

It handles trillions of search requests a year. SEO is a key consideration—when search is often the primary source of traffic to your website, being “search engine friendly” on any platform where people can search for your brand or business is critical.

What all this means is that enhancing your visibility and appearing higher in search results than your competitors can have a positive effect on your bottom line.

SEO is also critical because the organic search engine results page (or SERPs) is super competitive — dominated by search features (and warm PPC). SERP features include:

• AI Overviews.
• Knowledge panels.
• Featured snippets.
• Maps.
• Images.
• Videos.
• Top stories (news).
• People Also Ask.
• Carousels.

Good SEO work is also sustainable, which is why it is essential for brands and businesses. Once a paid campaign stops running, traffic ceases as well. Social media traffic is unreliable at any moment and a fraction of its former self.

SEO is the cornerstone of holistic marketing, where everything your business does counts. Once you know what your users need, you can apply that knowledge across your:

• Campaigns (paid and organic).
• Website content.
• Social media properties.

Organic search is one channel that brings the traffic you need for essential business goals (e.g., conversions, visits, sales). It also builds trust—a website that ranks well is pretty much considered authoritative or trustworthy, two things Google wants to reward with better rankings.

Types of SEO and specializations

Imagine SEO as a sports team. A potent offence and defence are required to score the win. But you also have to have fans (an audience).

Technical optimization (defence), content optimization (offence) and offsite optimization (fan engagement):

• Technical SEO: This refers to optimizing the technical components of a website.
• On-site SEO: Improving a website’s content for users and search engines.
• Off-page SEO: build brand assets (i.e., people, marks, values, vision, slogans, catchphrases, colours) and do something that will eventually improve brand awareness and recognition (i.e., constantly showing and growing expertise, authority and trust) and demand generation.

You have complete ownership of content and technical optimizations. This isn’t always the case over the off-page (you can’t directly impact links from other sites and whether platforms you depend on suddenly shut down or make a significant change). Still, those activities are a core part of this SEO trinity of success, regardless.

Technical optimization (technical SEO)

The technical aspects of a website need to be optimized at the beginning of your SEO roadmap.

It begins with architecture — building a website that search engines can crawl and index. Which is why, as Google’s trends analyst Gary Illyes once said in a Reddit AMA, in conversation with Shai’s three-word advice: “MAKE THAT DAMN SITE CRAWLABLE.”

You want to help search engines find and crawl your page’s content (e.g., text, images, and videos). Several key components fall within the technical SEO realm, including URL structure, navigation, and internal linking.

The other major piece of technical optimization is user experience. Search engines warn that fast-loading pages with good page experience are a must. Technical SEO includes Core Web Vitals, mobile-friendliness and usability, HTTPS, and non-annoying interstitials.

A second area of technical optimization is structured data (a.k.a. Schema). This code provides search engines with helpful information about your content, improving your visibility and position in search results.

SEO influences web hosting suppliers, CMS (content management systems), and website security.

Content optimization (on-page SEO)

In SEO, you must make your content appealing to two major groups: humans and bots. This means optimizing what your audience will look at (what’s on the page) and what search engines will look at (the code).

EVERYTHING IS ALWAYS ABOUT PUBLISHING USEFUL HIGH-QUALITY CONTENT!!! This entails understanding what your audience is looking for and combining this with data and guidance from Google.

When optimizing content for people, you want to ensure that it:

• Feel free to provide additional details about the author — if your bio includes a few lines, for example.
• Contains words and phrases that people might use to look for the content.
• Is it unique or original?
• Grammatical/spelling errors are minimal, but it is well-written.
• You are updated until October 2023.
• Featuring multimedia (images, videos, etc.)

This is why it supersedes your SERP competitors.

It is readable and built to allow others to process the information you’re trying to share (sub-headings, short paragraphs, bolding/italics, ordered/unordered lists, reading level, etc.).

Some essential elements for search engines to optimize for are:

• Title tags
• Meta description
• Header tags (H1-H6)
• Image alt text
• Open Graph metadata

Generative engine optimization (GEO) is a new speciality within content optimization. GEO is about optimizing your content for visibility in AI-driven search engines (or answer engines), such as Google’s AI Overviews and Gemini, OpenAI’s ChatGPT and SearchGPT, and Microsoft’s Copilot and Perplexity.

Brand and authority building (offsite optimization)

Some activities may not be “SEO” in a literal sense, though they can converge with and, in turn, help support SEO success.

Growing a website’s online presence through offsite SEO (the process of acquiring links to a website) is most closely related to link building. A diverse number of links pointing at your website from relevant (to you or your industry), authoritative, trusted websites can bring you significant benefits (e.g., rankings, traffic, etc.)

It’s better to have fewer links than a slew of low-quality links. The aim is to build up a lot of good links.

How do you get those links? Many website promotion techniques are interdependent with SEO.

These include:

• Brand building — and brand marketing: Methods intended to increase awareness and prestige.
• PR: Ways of doing public relations such that you are rewarded with editorially-given links.
• Content marketing: Videos, ebooks, research studies, podcasts (or being a guest on other people’s podcasts) and guest posting (or guest blogging) are prevalent types of content marketing.
• Social media marketing/optimization: Claim all the relevant platforms with your brand handle, fully optimize them, and publish relevant content.
• Directory listing management: Claiming, verifying and optimizing the information on platforms where information about your company or website may be listed and available for searchers (e.g., directories, review sites, wikis).
• Ratings and reviews: How to get, track and respond to them.

Most of the time, offsite, you’re referring to items that do not directly relate to your rank as a technical factor.

But again, every single thing your brand does here matters. You only want the audience to search for your brand and find you anywhere they could be.

As a result, some have attempted to redefine “search engine optimization” to mean “search experience optimization” or “search everywhere optimization.”

SEO specialities

There are also a few subgenres under search engine optimization. Every speciality area is unique to “regular SEO” and has strategies and distinct challenges.

Five of those SEO specialities are:

• E-commerce SEO: Category page optimization, product page optimization, faceted navigation measures, internal link structure management, product image management, product review management, Schema, etc.
• Enterprise SEO: This is the world of SEO done at the enterprise level. Usually, this means working with a website (or several websites/brands) with 1M+ pages – or it may depend on the organization’s size (usually those making millions or billions of revenue per year). Enterprise also usually involves delays in getting SEO changes implemented by the dev team, and multiple stakeholders must be involved.
• International SEO: This is global SEO for international businesses, done for multiregional or multilingual websites and optimized for international search engines, including Baidu or Naver.
• Local SEO: A type of SEO that focuses on optimizing websites to be found in local search engines’ organic results. Examples include the management and optimization of the presence of a business listing and reviews.
• News SEO: The most important aspect of news is speed. Until this is completely updated, you need to proactively ensure you are correctly indexed by Google as fast as possible and positioned in Google Discover, Google Top Stories, Google News, and everywhere else. You must also know best practices for paywalls, section pages, news-specific structured data, etc.

How does SEO work?

If this page appeared in a Google search, you most likely typed in something like that.

This guide is hosted on Organic SEO IT, a well-respected, authoritative source of expertise and knowledge on SEO topics (we’ve covered every significant change in SEO since 2006).

This What is SEO page was first published in 2010 and has earned hundreds of thousands of links.

These factors (and more) have contributed to this guide’s favourable reputation in search engines and have helped it rank consistently in the top 1-3 organic search positions in almost all major search engines for several years. It has accumulated signals that show it is an authority and a trusted source—and therefore, it deserves to rank when someone searches for SEO.

But let’s take a broader view of SEO. SEO, as a whole, works through a combination of:

• People: The individual or team doing the strategic, tactical and operational SEO work.
• Processes: What is done to improve work efficiency?
• Technology: Those platforms and tools.
• Activities: The final output or product.

How SEO works involves many other factors. This section will highlight the key ingredients of knowledge and process.

Six areas, used in conjunction, get SEO to work:

1. Understanding how search engines work

And I’m not talking about opting into the lists of businesses that show up when people search for businesses on every platform for any given reason, either — you need to get into the nuts and bolts of how the engine works technically and then make sure you are supplying all the right “signals” to influence that visibility.

So when it comes to traditional web search engines such as Google, four distinct stages exist for search:

• Crawling: Search engines discover pages on the web through crawlers that follow links or use sitemaps.
• Rendering: Search engines take the HTML, JavaScript and CSS information to generate how the page will look.
• Indexing: After search engines find your pages, they want to understand what they’re about and store them in a database — but not all pages on your website may be indexed.
• Ranking: Complex algorithms analyze various signals to determine whether a page is relevant and high-quality enough to be displayed when searchers enter a search query.

However, optimizing for Google search isn’t the same way you optimize for search on other platforms such as YouTube or Amazon.

For example, on Facebook, the content shown (Likes, comments, shares, etc.) depends on different factors, such as their popularity (engagement) or who users are connected to. For Twitter, signals such as recency, interactions, or the importance of the author are crucial.

Adding to the complication, search engines have added layers of machine learning to surface content, making it trickier still to say whether “this” or “that” equates to better or worse performance.

2. Researching

SEO is built on top of solid research. The types of research that will help your SEO performance include:

• Audience research: Knowing your audience or market is fundamental. What are their demographic and psychographic demographics? What are their pain points? What questions do they face that you can answer?
• Keyword research: Keyword research is finding and using the relevant and valuable search terms people use to find your pages, understanding the general demand for this search term, and determining how competitive it will be to rank for it.
• Research into your competitors: What are your competitors already doing? What have they done well, and where have they struggled? What are they creating in terms of content?
• Brand/business/client research: What do they want to achieve – and how can SEO help?
• Website analysis: Various SEO audits help companies find opportunities, and then, one, we hamper the competitors in organic search. Technical SEO Some audits include technical, link profile, and E-E-A-T. These are some of the theses. This allows you to assess the search intent behind a query (commercial versus transactional) and craft content that is more likely to achieve rankings or visibility.

3. Planning

An SEO strategy is your master action plan. You have to set goals and develop a road map—think of your SEO strategy as a Roadmap! Your journey will likely change and evolve, but the destination should stay the same.

Here are examples of what could be included in your SEO plan:

Setting goals (OKRs, SMART, etc.)

• Creating expectations (i.e., timelines/milestones).
• Defining, tracking and aligning meaningful KPIs and metrics
• Determining how projects will be produced and executed (In-house, outsourced or hybrid).
• Working with key stakeholders on coordination and communication.
• Tool/Technology selection and implementation.
• Part of the hiring, training and structuring of a team
• Setting a budget.
• Tracking and reporting on results.
• It was documented as a strategy and process.

4. Creating and implementing

After all the research is completed, it’s time to take action.

That means:

• New Content Creation: Guide your content team on what to create.
• Suggest or make improvements to current pages: This might involve updating and enriching the content, adding internal links, keywords/topics/entities, or any other way of further optimizing it.

It will include removing old, outdated, or low-quality content that does not rank well, drives converting traffic, or helps you achieve your SEO goals.

5. Monitoring and maintaining

You have to be aware when something fails or breaks on your website. Monitoring is critical.

You must know when traffic drops to a key page, when pages are slow or unresponsive, or when pages fall from the index. You must also know if your website crashes, links stop working or other major disastrous problems.

6. Analyzing, assessing and reporting on performance

You must know when something goes wrong or breaks on your website. Monitoring is critical.

You need to know when traffic declines to a key page, when pages become slow and unresponsive, or when pages drop out of the index. You also need to know if your whole website goes down, links break, or another potentially catastrophic issue exists.

Performance analysis, evaluation and reporting

What you can’t measure, you can’t improve — SEO If you want to make data-driven decisions about SEO, you will have to use:

• Website analytics: (At a minimum, institute free tools such as Google Analytics, Google Search Console and Bing Webmaster Tools) to capture performance data.
• Tools and platforms: Most “All-in-one” platforms (or suites) provide multiple tools, while you can also decide to use only select SEO tools to track performance based on particular tasks. Or, if you have the means and none of the tools built by others do exactly what you need, you can create your own.

Once you’ve gathered the data, you must provide a progress report. Reports can be created with software or by hand.

Performance reporting should be story-like and done over a meaningful time interval, usually comparing previous report periods (e.g., year on year). This may vary based on the type of website (typically monthly, quarterly, or whatever the case may be).

SEO is ongoing

Search engines, user behaviour, and your competitors are constantly changing. Websites change and move (and break) over time, and content gets stale.

How SEO evolves

SEO is constantly changing because it is a service and discipline exercised at the coalface of how humans interact with information on the web.

Thinking of the web and search engines in a larger societal context matters most.

Libraries, for instance, have existed for millennia. Documentary and evidence suggest that such places, where civilizations’ accumulated wisdom would be stored, have lived in cultures worldwide since at least the seventh century B.C.E.

In this sense, the web (an archive of bits and a catalogue of dank memes) is barely an adult. As a search engine, Google has only been around since September 1998.

The web and the techniques we use to search for and retrieve what we want from the web are novel in the context of human memory and behaviour.

We utilize technology devices such as computers, mobile phones and home assistants to access search engines. With the advancements of technology, new ways of behaviour in terms of how we use and adopt are also coming into play.

This has implications for how search engines evolve their product capabilities and look-and-feel, which informs adaptive changes to SEO.

Let us look at some of the significant ways SEO changes:

Adapting to technology

We said that technical SEO is one of the four broad categories (or areas) of SEO. However, technology has shifted over the last ten years, and most of what an SEO does (tasks and tactics) never existed a decade ago.

• AI-Driven Search Results: In 2023, significant changes to how AI drives some of the search results you see and how frequently those results appear were coming to the table—particularly from Google, with AI Overviews and Bing’s generative search results.
• Mobile-first indexing: Ten years ago, the SEO space was always caught up in preparing well-optimized websites for mobile phone searches so they would appear in search engines when accessed from a mobile phone. By 2021, 63% of Google searches in the Competitive Average (U.S.) were happening on a mobile phone, and the Google Index now ranks a site’s mobile performance as its lead indicator (completed 2023).
• Speed & user experience: With device usage and improved capabilities, so does WiFi in terms of speed and penetration—and then our behaviours and expectations of services we consume. So, back to what seemed mundane a decade before when using a mobile phone. Like decades back in the noughties, consumers get very annoyed when they experience anything like wading through “waiting” pages, pages loading slowly, pages where parts are missing, etc.

SEO practice is out of step or solon in the three areas of rapid change above. As we move through these three areas, many component changes, features, and technologies today are part of SEO’s bread and butter.

SEO as a service

According to the SEO Services market research report, the SEO market is expected to increase from $75.13 billion in 2023 to $88.91 billion in 2024, an annual growth rate of 18.3%, reaching $170 billion in 2028, at a CAGR of 17.6%, data up to October 2023 is reported.

With search engines and search as ubiquitous as they are, mobile phone capabilities, and the ever-changing economic climate, it is no surprise that SEO is well-established as a professional service.

SEO is a marketing discipline and a job title. There is SEO and search engine optimization.

There are endless different buggy roles and responsibilities in search engine optimization and tonnes of specialisms that mirror both the words of SEO and the skills and capabilities needed.

It can be daunting to learn how to start a career in SEO.

Unlike law, accounting, or other established professions, no formally high-education courses or professional qualifications are established and recognized globally for product development. Plus, most optimization practices need some analysis of performance status and planning where and how to improve above the metrics that matter, so there are a lot of data-skill requirements, too.

The best place to start with website performance data is free data sources like Google Analytics and Google Search Console. Moreover, using Semrush data, we’ve compiled a set of free tools that could provide a nice entry for you to perform data:

• FREE Keyword Difficulty Checker
• Free Keyword Ranking Checker
• Free Keyword Generator
• Free Backlink Research
• Free Website Traffic Checker
• DA Checker — Free Website Authority Checker
• Free SERP Checker
• Free Competitor Analysis Tool

At first glance, entering a new discipline might seem intimidating, but it’s very easy to get started. We’ve also gathered a few more resources below.

Final Thought

As one of the most dynamic core digital marketing strategies, Search engine optimization is essential for online visibility. With more innovative search engines improving user intent, businesses must evolve their marketing strategies to include technical SEO, on-page SEO, and off-page SEO strategies. It’s not simply about climbing up the rankings but ensuring your content benefits the appropriate audience at the proper time.

With search moving beyond traditional engines to platforms like TikTok, YouTube and Amazon, SEO is no longer Google’s game — it’s about optimizing for any places your audience is searching. SEO is not an expense to be avoided but an investment that will help them grow in the long run, build trust, and stay competitive.