In this guide, we’ll tell you a little bit about how search engines work. This will talk about the crawling and indexing processes, as well as ideas like crawl budget and PageRank.
Search engines use their own web crawlers to go through hundreds of billions of pages. People often call these web crawlers search engine bots or spiders. A search engine finds its way around the web by downloading pages and following links on them to find new pages that have been added.
How is the Search Engine Index?
When a search engine finds a web page, it adds it to an index, which is a data structure.
The index has all the URLs that have been found, along with a number of relevant key signals about each URL’s content, such as:
- The keywords found in the page’s content—what does the page talk about?
- Using microdata called Schema, what kind of content is being crawled? What is on the page?
- How recent the page is – when was it last changed?
- How people have used the page and/or domain in the past. How do people use the page?
What is the Point of a Search Engine Algorithm?
The goal of the search engine’s algorithm is to give the user a set of relevant, high-quality search results as quickly as possible.
The user then chooses an option from the list of search results. This action, along with what the user does next, is added to what the search engine learns, which can affect its rankings in the future.
What Happens When a Search is Finished?
When a user types a search query into a search engine, the index is used to find all of the relevant pages. An algorithm is then used to put the relevant pages in a set of results in a way that makes sense.
Each search engine has its own way of figuring out which results are the best. For example, a page that ranks well in Google for a certain search query might not rank well in Bing for the same query.
In addition to the search query, search engines use other relevant information to come up with results.
- Location: Some search terms depend on where you are, like “cafes near me” or “movie times.”
- Language detected: If a search engine can figure out what language the user speaks, it will return results in that language.
- Previous search history: When a user types in a question, search engines will give different answers based on what that person has already looked up.
- Device: Depending on the device from which the query was made, the results may be different.
Why Might a Page Not Get Indexed?
There are a number of reasons why a search engine might not index a URL. This could be because:
- Robots.txt file exclusions is a file that tells search engines what parts of your website they shouldn’t look at.
- The noindex tag tells search engines not to index that page or to index another page that is similar (canonical tag).
- Search engine algorithms think that the page is of low quality, has little content, or has content that is already on other pages.
- The URL that takes you to an error page (e.g. a 404 Not Found HTTP response code).