Most search engines have three parts: a crawler, an index, and a search interface. Let’s
look at each part individually to get a better understanding of them. Each part has its
own role to play in the process, with all parts working together to make searches
possible.
1. The Crawler
Also known as a “spider” or “bot”, this part of the search engine wanders the Web,
following links and picking up information for its database. Crawlers do most of their
work at times of the day when search engines are less busy, typically visiting frequently
updated pages more often. This is something to keep in mind when you are working on your
pages.
Your site’s title and content are the most important thing to a crawler. One of the best ways
to raise your site’s search engine ranking for specific key words is to implement them
into your title and your content.
2. The Index
Once the crawler has collected all that text, it is then stored and indexed. This allows
people searching for keywords and phrases to get results relating to what they were
searching for – their search results, displayed on search engine result pages (SERP). To see this in action, go to a search engine and enter a search phrase. You’ll see some text on
the page saying something like “results 1-10 of 1,234,000”. This means that the search
engine’s index contains 1,234,000 pages it believes are related to the search phrase entered.
In order to understand rating systems more thoroughly, consider your own site. When you
place links on your site you generally do so to increase the understanding of web site visitors on the content of your site.
If every site in a particular field of interest links to one specific site, this site is
probably very important to that field and should, therefore, be listed highly in the
lists of search engine results. This is the basic ideology of how Google and other search engines display SERPs.
3. The Interface
Search engines provide a public interface for users who want to find information on the
Web. They type the word or phrase they’re searching for, and the interface will run an
algorithm to find the pages relevant to their search and display them.
These algorithms are an important part of the SEO (Search Engine Optimization) business. You’ll notice when the algorithms change, the rankings of your web site may change. No two search engines have the same algorithms. They all work differently, with their unique features, and they will all rank your web site in their own way.