Crawling

Crawling is the first thing that happens to any page before it can rank. A search engine sends out an automated program, Google calls its bot Googlebot, that fetches a URL, reads the response, and pulls out the links on that page so it can go fetch those too. The whole web gets discovered this way: one link leading to the next, over and over.

Here is the part most people miss. Crawling is not the same as ranking, and it is not even the same as indexing. Crawling just means the bot grabbed a copy of your page. What happens after that is a separate story. But nothing downstream happens at all if the crawl never occurs, so this is where your technical SEO foundation starts.

How a crawl actually works

1. 1The crawler pulls a URL off its queue, often discovered from a link, a sitemap, or a previously known page.
2. 2It checks robots.txt to see whether it is allowed to fetch that URL.
3. 3It sends an HTTP request and reads the status code and the response body.
4. 4It extracts links from the HTML and adds new, allowed URLs to the queue.
5. 5It schedules the page for indexing evaluation, where rendering and content analysis happen.

That queue is the thing to keep in mind. Google does not crawl your whole site in one sweep. It prioritizes based on signals like how often a page changes, how many internal and external links point at it, and how important the rest of your site looks. A page buried five clicks deep with no links pointing to it can sit uncrawled for a long time.

What stops a crawler cold

• A Disallow rule in robots.txt that blocks the URL or the directory it lives in.
• Orphan pages with no internal links pointing to them, so the bot never finds the URL.
• Server errors or timeouts that make the page unfetchable when the bot arrives.
• Endless URL parameter combinations that trap the crawler in low-value variations.
• Login walls, forms, or JavaScript actions that hide content behind interactions a bot does not perform.

It also helps to remember that crawling is continuous, not a one-time event. Search engines come back again and again, and how often they return depends on how fresh and important a page looks. A homepage or a popular article might get crawled many times a day. A static page nobody links to and nobody updates might get crawled once every few weeks. That cadence directly affects how quickly your edits, new content, and fixes actually show up in search, which is why a healthy crawl pattern is something worth watching over time rather than checking once and forgetting.

When you want to see crawling at scale, pull your server logs and look at how the bots move through your site. That tells you exactly which pages get fetched often, which get ignored, and where crawlers waste their time. For the full walkthrough, see my technical SEO guide, and if your pages depend on scripts to render content, read the JavaScript SEO guide too.