In one sentence: Search engine optimization (SEO) is the work of making a website easy for a search engine to find, understand and trust, so that when someone types a question the search engine answers with your page.
Everything else on this page is the “how” behind that sentence, told the way I would tell it to a local plumber who has heard the word a hundred times and never had it explained.
So what is a search engine actually doing?
Picture Google as a librarian who has already walked every aisle of the internet, opened every book, and written a card for each one. When you ask “who fixes water heaters near me?”, it does not read the books again. It looks at its cards, picks the ones that answer you best, and puts them in order.
Google describes its own process in three stages, and the names are worth knowing because every SEO conversation uses them.
Crawling. Automated programs, which Google calls crawlers, “explore the web regularly to find pages to add to our index.”[1] A crawler is a program that follows links from page to page, reading what it finds. If nothing links to your site and you never told Google it exists, the crawler may never arrive.
Indexing. Once a page is crawled, Google reads it and “stores the information in the Google index, a large database.” This is the librarian writing the card. Google is blunt about one thing here: “indexing isn’t guaranteed; not every page that Google processes will be indexed.”[1] A page can be crawled and still be left out of the library.
Serving and ranking. When someone searches, Google pulls the indexed pages that match and orders them “by hundreds of factors,” including where the searcher is, what language they use and what device they are on. Google also states that it “doesn’t accept payment to rank pages higher.”[1] The ads at the top are a separate auction; the ranked list underneath is decided by the algorithm.
SEO is the craft of helping your site succeed at all three stages: being found by the crawler, being understood well enough to be indexed, and being judged a good enough answer to be served near the top.
What does “ranking” mean, in plain terms?
Ranking is just position in the list. Position one is the first result under the ads; position ten is usually the last on page one.
The reason people obsess over position is that the click curve is steep. In a study of 12.2 million queries, the number-one organic result got 27.6% of clicks, the top three together got 54.4%, and the tenth result got 2.7%. All of page two combined got 0.63%.[2]
Less than one click in a hundred goes to anything on page two. For a local plumbing site, moving from eleventh to the top three for “water heater repair near me” is the difference between a share of 0.63% and a share of 54.4% of the clicks.[2]
What did “page one” mean for a local business?
For about fifteen years it meant the phone rang.
Here is the historical arc, told as history. In 2005, the share of American internet users who used a search engine on a typical day jumped from 30% to 41%.[3] By January 2011 the internet had become the number-one source Americans used to find information about local businesses, at 47%, ahead of newspapers at 30%.[4]
The businesses that had lived on the printed phone book felt that shift directly. Yellow Pages print references fell from 15.1 billion in 2002 to 13.4 billion in 2006, according to the industry’s own usage study as quoted in company filings.[5] Idearc, the company that published Verizon’s directories, filed for Chapter 11 on March 31, 2009.[6] R.H. Donnelley, another of the big three, filed that May.[7] Both carried enormous debt, and the recession was the trigger, but the trend underneath was people looking things up in a search box instead of a book.
The businesses that moved early got the calls the book used to bring, at no per-call cost.
What does a search engine look at to decide?
Google itself says “hundreds of factors,”[1] but the broad shape is well understood. It comes down to three questions the engine asks about your page.
Can I read it? Is the page reachable, fast, working on a phone, and written in a way a program can parse?
Is it about what the person asked? This is relevance. If your page says “we do everything” and never mentions water heaters, it will not be the best answer for “water heater repair.” Pages that clearly cover one service in one place tend to win for that service.
Do others vouch for it? This is the trust signal. Links from other reputable sites, mentions of your business name and address in consistent form across the web, and reviews all tell the engine that real people and real organizations recognize you.
For a local business there is a fourth question that matters more than the others: where are you? Google runs a separate ranking for local results, the map with three businesses under it, and the inputs there are different. A survey of 47 local-search practitioners rated Google Business Profile signals, review signals and user-behavior signals as the top three factors, out of 187 considered.[8] Your Google Business Profile, the listing that appears on Maps, is a ranking input in its own right, separate from your website.
Let me try an example. What would SEO look like for a local plumber?
Say you run a four-truck shop in Natomas. Someone in Elk Grove types “tankless water heater install near me” into their phone.
Google has to decide, in a fraction of a second, which plumbers to show. It checks its index for pages about tankless water heater installation. It checks its Business Profile data for plumbers whose service area covers Elk Grove. It looks at which of those businesses have reviews that mention water heaters. It looks at which sites load quickly on a phone and clearly state what they do and where.
If your site has a page titled “Tankless Water Heater Installation in your city and the next one over,” your Business Profile lists “water heater installation” as a service, and twelve of your Google reviews mention water heaters by name, you have given the engine three consistent signals pointing at the same answer. That is SEO. Not a trick, a set of facts stated where the engine looks.
The shop whose home page says “Quality plumbing, call today” and nothing else has given the engine almost nothing to work with.
What changed with AI Overviews?
On May 14, 2024, Google began rolling AI Overviews out “to everyone in the U.S.”[9] An AI Overview is a written answer, generated by Google’s AI, that appears above the ranked list for many searches. Google said it expected to bring the feature “to over a billion people by the end of the year.”[9]
The ranked list is still there. What changed is what people do with it.
Pew Research tracked 900 American adults through 68,879 real searches in March 2025. When an AI summary appeared, people clicked a traditional result on 8% of visits. When there was no summary, they clicked on 15%. Only 1% clicked a link inside the summary itself. And 26% of visits ended right after the summary, compared with 16% otherwise.[10]
Measured across 300,000 keywords, an AI Overview cut clicks to the number-one result by 34.5% between March 2024 and March 2025.[11] Across the whole US, the share of Google searches ending with no click to any website rose from 58.5% (2022 to 2024 panel) to 68% in early 2026: 231 clicks to the open web per 1,000 searches, down from 360.[12][13]
To say it plainly: people did not stop searching. Google reported in July 2026 that search queries were at an all-time high.[14] What went down is the number of clicks a ranked page receives, because the answer is now written out above the list.
So SEO did not stop mattering. It gained a second job. The first job is still to rank in the list. The second is to be one of the sources the AI answer is built from, because being named inside that answer is where attention now goes. That second job has its own name, and it is the subject of the next page.
What this is not
SEO is not paying Google. The ranked results cannot be bought. Ads are a separate product, marked as ads, sold in an auction.
SEO is not a one-time setup. The index is rebuilt continuously, competitors publish new pages, and Google changes its ranking systems many times a year.
SEO is not keyword stuffing. Repeating “plumber near me plumber near me” was a tactic in 2008 and is a liability now. The engine reads for meaning, not word count.
SEO is not the same as your Google Business Profile, although they overlap. Your website ranks in the list. Your profile ranks in the map. Both need attention, and they need to agree with each other.
SEO is not social media. Posting on Instagram does not, by itself, change how Google indexes your website.
Where it is going
Forecasts, labelled as forecasts
These are forecasts, and I am labeling them as such.
Forecast one: the list stays, the answer grows. Google has no announced plan to remove ranked results, and its own numbers say queries are rising. But AI Overviews appeared on a growing share of searches, with estimates from 18% of real users’ searches.[10] to 43%[15] to 59.7% on one keyword panel[16] The range depends on which searches you measure; the direction is the same in every dataset.
Forecast two: the sources inside the answer will be judged differently from the ranked list. Only 19% of the sources cited in AI Overviews overlapped with the organic top ten, in one February 2026 analysis.[16] If that holds, ranking well and being cited will continue to be related but separate goals.
Forecast three: for local businesses, the profile and the reviews carry more of the weight. In 1.9 million citations across local AI answers, Google Business Profile was the single most cited source at 28.63%, and businesses’ own websites made up 42% of citations.[17] The website is not going away as the input. It is being read by a new reader.
One forecast that did not come true is worth remembering. In February 2024, Gartner predicted that “by 2026, traditional search engine volume will drop 25%.”.[18] Volume did not drop; Google reports record highs[14] What fell, by more than 25%, was clicks to websites per search. Anyone who tells you where this is going with certainty is guessing, including me.