Before a page can rank, search engines have to find it, which happens through crawlers following links across the web, then understand it by indexing the content, storing it alongside everything learned about what the page covers. A page that is confusingly written or technically broken can get crawled and still never get properly indexed, which makes it invisible in search results no matter how good the writing is.
Ranking is the stage most people think of as SEO, when someone searches, Google sorts through everything relevant in its index and weighs relevance, quality, trustworthiness, and user experience to decide what deserves the top spots. No single factor decides this alone, it is an accumulation of dozens of smaller signals, which is why SEO rarely has one clean fix.
The work splits into two halves, on-page SEO, everything controlled directly on a site like content, structure, and speed, and off-page SEO, everything happening elsewhere that still affects the site, like other websites linking back or mentioning the brand. Both matter, a technically perfect site with no outside credibility struggles against established competitors, and a well-linked site with thin content will not hold its position once visitors start leaving quickly.
Crawl budget is a real, if often overlooked, part of this process: search engines only spend so much time crawling any given site, and a robots.txt file blocking the wrong pages, or a site full of low-value duplicate URLs, can waste that budget on pages that don't matter while important pages get crawled less often than they should. Keeping crawlable content focused on what's worth indexing helps search engines spend their limited attention where it counts.
None of these stages work in isolation, a page can be perfectly crawlable and indexed but still rank poorly if the content itself doesn't serve what the searcher was looking for.
Search engines also weight freshness differently depending on the query. A page about a fast-moving topic (current events, pricing, software features) needs regular updates to stay competitive, while a page answering a timeless question can rank well for years with only occasional revisions. Treating every page as needing constant rewrites wastes effort; the more useful habit is checking which pages actually cover a moving target and prioritizing those for updates.
User signals — how long someone stays, whether they click back to the search results immediately, how far they scroll — feed into ranking indirectly, not because Google tracks each visitor individually in a simple way, but because aggregated behavior across many searchers reveals whether a page satisfied the query. A page that gets clicked constantly but immediately abandoned is a signal something about the content didn't match what the searcher expected, even if the title and meta description were technically accurate.