What Is a Search Index?

**# What Is a Search Index? When you do a simple internet search, no matter what you're looking for, you receive results instantaneously (or as fast as your internet connection allows.) With millions of websites out there, how does this happen so fast? You'd think that since the search engines need to go through those websites in order to produce the results, the process would take longer. Well, thanks to search indexes, getting relevant Google results takes a matter of seconds, not minutes. But how do search indexes work?

A Search Index Works Like a Book Index

The best way to describe a search index is by comparing it to a book index. If you wanted to find something in a large history book, rather than go through the entire thing page by page, you'd turn to the index and look for the subject or person that you want to learn about. This saves time and gives you an easy way to find exactly what you're looking for. A search index is very similar. Only, instead of providing you with a list of book topics and subjects, it gives search engines a list of keywords that are discussed on the site. While there are no page numbers, as there would be in a book index, there are web pages, or URLs, instead. These direct the search engines to the correct part of the site, allowing them to directly pull up the page that contains the information when you conduct a search.

How are Search Indexes Created?

Unlike a book index, which a human creates, a search index is built by bots. These tiny bots crawl through websites to see which keywords are used, turn them into a search index, and make a list that they take back to the search engine. The search engine then takes this index and places it in its database. Depending on the site's contents and how well attuned it is to Google's algorithms, the site may appear anywhere in someone's search results from page 1 to page 30 and beyond. It all depends on the main search engine's reports from the web crawlers. Since the crawlers can go over a website regularly, noting any changes that are made, the search index is regularly updated, and the search results can change based on what the web crawlers find.

How Do Search Results Appear?

A search index plays a large role in the search results you receive when you Google search for certain keywords. If you searched, for example, for "dog food," Google's search engines would go through all of their search indexes to pull up the best results. All of this is done very quickly, in a split second or two, to get the answers you're looking for without taking a long time to go through the databases. If it weren't for search indexes, those searches would take an even longer time, and the results might be less than accurate.

What About a Search Engine Ranking?

Asearch engine ranking is what Google and other search engines create from their web crawlers' information. There are many things that they look for to give searchers a list of the best quality sites out there; otherwise, instead of searching for "dog food" to pull up a list of dog food companies, who knows what you'd get. Google updates its algorithms regularly to ensure that the best sites are the ones near the top. Although it changes these criteria and often keeps it quiet so that sites can't use black hat tricks to get their questionable websites to the top of the results, there are some things that it shares. For example, a website that uses secure socket layers (SSL, or the "s" in HTTPS in the web address) is one thing that is rewarded.

What Exactly Are the Web Crawlers Looking For?

A web search pulls up some very specific information, including the URL of the pages and the keywords that are used on them. These are just a few of the things that a web crawler pulls and adds to the index that it creates. Here are a few others:

Titles and Headers

Webpages use a variety of titles and headers to break up their content and make it easy to read.**