How Search Engines Crawl and Index Your Site

Search engines like Google don’t just stumble upon your website and show it to users automatically. To appear in search results, your content first needs to be discovered, understood, and stored/cached by search engines. This happens through two key processes: crawling and indexing.

Both are essential for SEO. If your content isn’t crawled, it won’t be seen. If it’s not indexed, it won’t be ranked.

Crawling

Crawling is the process where search engines send automated bots (often called spiders or crawlers) to find and scan web pages. These bots begin by visiting a known list of URLs (such as those submitted in a sitemap or previously discovered pages) and then follow the links on those pages to find more content.

When a bot visits a page, it reads the HTML code, looks at the links, analyzes headings, identifies metadata, and makes note of any resources like images or scripts. It may also check instructions in your robots.txt file to see if it’s allowed to crawl certain areas of your site.

Crawling is not a one-time event. Search engines regularly revisit sites to find new pages and check for updates to existing ones. However, how frequently they crawl your site depends on factors like your site’s authority, content freshness, technical health, and how often you publish new material.

Indexing

After a page is crawled, it moves to the next stage: indexing. Indexing is the process where the search engine analyzes the page’s content, evaluates its relevance and quality, and stores the page in its massive database (called the index).

If a page is not indexed, it cannot appear in search results, even if it was crawled successfully. Pages can be excluded from indexing for a variety of reasons—technical issues, poor content quality, duplication, or specific instructions from the site itself (such as a noindex tag).

During indexing, Google looks at:

The page’s content (text, images, structured data)
Its internal and external links
Metadata such as title tags and meta descriptions
Canonical tags that suggest preferred versions of pages
Page experience signals like mobile usability and speed

Google then decides how to categorize the page and which keywords it might be relevant for.

How Search Engines Find New Pages

There are several ways a search engine might discover your content:

Internal links - If you link to a new page from an already indexed page, crawlers can follow that path.
Sitemaps - XML sitemaps submitted to Google Search Console offer a direct list of pages you want indexed.
Backlinks from other websites - When another indexed site links to yours, crawlers can follow that link to discover your page.
Manual submission - You can request indexing for individual URLs via Search Console, especially for new or updated content.

In most cases, the fastest and most reliable method is a combination of internal linking and sitemap submission.

Help Search Engines Crawl Your Site

Crawlability depends on how easy it is for search bots to move through your website and access its content. To support efficient crawling, ensure:

Your site has a clear navigation structure and internal linking logic
Pages are not blocked in robots.txt unless intentionally excluded
There are no unnecessary redirects or broken links
JavaScript doesn’t hide important content from bots
URL structures are clean and consistent

Large websites should also pay attention to crawl budget - a limit on how many pages a search engine will crawl in a given time. Wasting crawl budget on low-value or duplicate pages can prevent important content from being discovered quickly.

Ensure Your Pages Get Indexed

Even if a page is crawlable, it might not be indexed. To increase the likelihood of indexing:

Make sure the content is original, relevant, and useful
Avoid thin or duplicate pages
Check for noindex tags or canonical issues
Use structured data to help search engines understand the page
Keep your sitemap updated with priority pages
Submit high-priority URLs manually in Search Console when needed

If your pages aren’t being indexed, Search Console’s Coverage and URL Inspection reports can help identify the reason - whether it’s a technical block, a directive like noindex, or simply low content quality.

How Often Do Search Engines Re-Crawl and Re-Index?

There’s no fixed interval. Some pages are crawled daily, others weekly or even less frequently. Fresh content that gets updated often tends to be crawled more regularly, as do high-authority pages. You can speed up re-indexing by updating your sitemap or requesting a re-crawl through Search Console.

That said, constant manual re-submission is unnecessary unless you’re dealing with critical updates or time-sensitive content. Focus on creating crawlable, index-worthy pages, and the system will work as expected in most cases.