What is SEO, in simple terms: how search engine optimization works

What SEO is, in simple terms

What the acronym stands for: Search Engine Optimization

SEO is short for «Search Engine Optimization» — literally, optimizing a site for search engines. It’s sometimes called «search optimization,» and informally people just say «SEO.»

A search engine is a service like Google or Yandex that selects pages from the internet in response to a query. A query is the words a person types into the search box.

In casual speech, «SEO» is sometimes confused with «CEO» — the term for a company’s chief executive. These are different things, and a CEO has nothing to do with search.

What SEO does for a site

Google frames the job of SEO this way: help search engines better understand your content, and help users discover your site. If a search engine understands what a page is about, it can show it to the people looking for exactly that.

SEO works with demand that already exists. People search for products, services and answers on their own. The goal is for those queries to surface pages that genuinely answer them. From this comes a simple principle: a page exists because it covers a person’s task, not for the sake of publishing volume.

In everyday use, the same work is called «SEO optimization» or «SEO promotion.» The substance is the same: make the site understandable to search and useful to people.

How search engines find and display pages

For a page to appear in the results, a search engine has to find it, process it, and decide that it fits the query. Google and Yandex describe this path differently, so let’s look at each one separately.

Google: crawling, indexing, serving results

Google describes three stages of how search works:

1. Crawling. Automated programs — robots — download text, images and video from sites. A robot, or crawler, is a program that visits pages and extracts data about them. Google’s is called Googlebot.
2. Indexing. Google analyzes a page’s content and stores information about it in the index. The index is a large database that the search engine later selects results from.
3. Serving results. When a person enters a query, the system offers the most relevant results. This takes into account things like the user’s location, language and device type.

None of these stages is guaranteed. Google states directly that it doesn’t guarantee crawling, indexing, or showing a site in search results. It primarily finds new pages through links from other, already-crawled pages.

Yandex: crawling, indexing, building results

Yandex’s help describes four stages:

1. Crawling the site. The robot decides on its own which sites to visit and how often. It learns about pages, among other ways, through internal and external links, and from the sitemap file — a list of a site’s addresses for search engines.
2. Downloading and processing data (indexing). The robot determines a page’s content and stores it in its database.
3. Building the database of pages that can appear in search. Algorithms decide which pages can make it into the results. For example, pages blocked from indexing and duplicates don’t make it into this database.
4. Building the search results. The algorithm assesses a page’s quality: how well the content matches the query and how useful it is to the user.

Yandex also warns: not every page on a site can be seen in search.

Where SEO fits into this chain

SEO helps at every stage. A page needs to be findable and crawlable. It needs to make it into the index. And its content needs to make clear which question it answers.

If an important page isn’t showing up in search, it’s worth checking the earlier stages of the chain. A separate article covers what to do if a page isn’t making it into the index. The reverse task also comes up: utility pages get removed from search on purpose. How to deliberately block a page from indexing is covered separately.

In our view, the same fundamentals matter for systems that compose answers from web pages too. We covered how the SEO foundation relates to generative search in a separate article.

What SEO consists of

SEO isn’t a single setting but several connected areas. What follows describes what the discipline is made of, not a sequence of work.

Technical foundations

The technical foundation is everything that lets a robot find pages and process them correctly. Google, for example, advises including words useful to users in page addresses, and grouping thematically similar pages into directories. Having the same content at different addresses doesn’t break Google’s rules, but it’s inefficient.

This also includes the crawling rules for robots: which sections are open for crawling, and which aren’t.

Demand, keyword research and site structure

SEO starts with a question: what are people searching for in your topic? The set of such queries is called keyword research. It matters to understand not just the words but also what task a user is solving with a query: finding out, comparing, or choosing.

Structure follows from demand: which pages are needed and how the sections connect to one another. More on how to collect the queries people search for your topic with, and how to design sections and page addresses.

Content

Content is text, images, video, and everything a person sees on a page. Google describes good content as helpful, reliable, and people-first. Text should be easy to read and well structured.

We covered how to write copy that answers a query separately.

Internal links

Internal links lead from one page on a site to another. Google finds most pages precisely through links. The link text can indicate what the page it points to is about. For people, these links help with moving on to the next step.

The article on internal linking covers how to connect a site’s pages with links.

Links from other sites, and reputation

Links from other resources also help search engines find pages. Yandex learns about pages through external links, among other signals; Google learns through links from already-crawled pages. Google also mentions word of mouth, where people familiar with a site tell their friends about it.

The sustainable path is for a site to get linked to and talked about because it’s useful. Google classifies buying or selling links that affect ranking, and excessive link exchanges, as link spam.

Measurement

Both search engines have tools for site owners. Google Search Console is a free service. In it, you can confirm that Google is finding and crawling the site, spot indexing issues, and see which queries pages appear for in the results.

In Yandex Webmaster, you can check how often Yandex’s robot visits the site and look at statistics on search queries.

On-page and off-page optimization

SEO areas are often split into on-page optimization — what’s done on the site itself — and off-page, what happens outside it.

Area	On-page or off-page	What it includes
Technical foundation	On-page	Page crawlability and indexability, URLs, duplicates
Keyword research and structure	On-page	Queries, site sections, the connections between them
Content	On-page	Text and other page material
Internal links	On-page	Links between the site’s pages and their anchor text
Links from other sites, mentions, reputation	Off-page	Links to the site and mentions of it on other resources

The split is approximate; the areas are connected. Good copy won’t work if the search engine can’t index the page. «Basic SEO» usually refers to the technical foundation and on-page optimization — what’s under the site owner’s control.

White-hat SEO and search engine rules

Google and Yandex publish rules for site owners. Google calls web spam the techniques that deceive users or a search engine to boost a site’s ranking. Sites that break the rules can rank lower in search results or not appear there at all. Yandex writes that its algorithms can apply restrictions that affect the ranking of an entire site or its sections.

Among the violations, the search engines name, for example:

• cloaking: visitors and search robots are shown different content;
• doorway pages — pages created specifically to attract users for certain queries;
• hidden text and links that are visible only to search engines;
• text meant to manipulate search: for Google, excessive keyword stuffing; for Yandex, SEO copy that’s useless to the user;
• links built to influence search rather than as a genuine recommendation to visit a resource;
• artificially inflating traffic — Yandex calls this simulating user actions.

White-hat SEO is work within these rules: with real demand, a technical foundation, structure, useful content, and natural links. Gray-hat SEO refers to techniques that sit at the edge of the rules and try to influence search while bypassing any benefit to people. We stick to sustainable SEO methods, without manipulative tactics, hidden schemes, or mass spam. Yandex phrases the general principle this way: focus on users’ interests, not on search engines.

What SEO doesn’t guarantee

• Top rankings. Google has no recipe that would automatically put a site in the top positions. No one can guarantee first place in Google’s search results.
• Every page being shown. Search engines decide for themselves what to display: Google doesn’t guarantee indexing or display, and not every page on a site can be seen in Yandex search either.
• Unchanging results. Search changes, and other sites compete for the same queries. This is our own explanation, not a search engine rule.
• Results from a one-time setup. The site, demand, and search itself keep changing, which is why SEO is ongoing work.

A spot in Google’s organic results can’t be bought: the company doesn’t charge for crawling sites more often or for boosting their position in search results. This is what sets SEO apart from search advertising.

If you’re curious what ongoing work on a site looks like, we’ve described it on the service page.

How to tell whether your site needs SEO

What to check	What it means	What to do
Are people searching for your products, services, or topics	If there’s almost no demand, SEO is unlikely to become your primary channel	Look at the queries for your topic before starting work
Are important pages showing up in search	A search engine can’t show a page that isn’t in the index	Start with indexing — see the link to the breakdown above
Is it clear what question each page answers	If not, it’s hard for search to match the page to the query	Clarify what each page is for and the section structure
Are you planning a new site or a move	It’s easier to account for search requirements up front than to fix them after launch. Google says bringing in an SEO specialist is especially helpful before building a new site or redesigning an existing one	Bring SEO in at the design stage
Do you have the resources for ongoing work	SEO isn’t a one-time setup	Decide who will work on the site, and how often

These are recommendations, not a rule that «everyone needs SEO.» If you’re unsure, start by diagnosing the current state: a separate article describes what gets checked in an SEO audit.

Frequently asked questions

How is «SEO optimization» different from «SEO promotion»?

In everyday use, these are nearly synonyms. «Promotion» more often refers to ongoing work on a site, or to the service itself, while «optimization» refers to changes made on the site. Both terms share the same substance, described in the first section.

Can SEO be handled in-house, without an agency?

Yes. Google writes that a small business can do almost everything itself. The free Search Console and Yandex Webmaster are there for that. In our view, a specialist becomes necessary for complex technical issues, large sites, and site moves.

When will SEO start delivering results?

There’s no way to name a timeline in advance. It depends on the site’s condition, competition in the topic, the amount of work, and how often search engines recrawl pages. It’s more honest to track changes visible in Search Console and Webmaster rather than aim for a specific date.

Does a small or new site need SEO?

The principles are the same as for a large site. It’s easier for a new site to build in a clear structure and technical foundation from the start than to fix them later. What to check first is described in the section «How to tell whether your site needs SEO.»