What Is a Search Engine?
A search engine is a tool used to find data based on a particular input. Web search engines are one example where you can enter a word or phrase to find web pages that match those terms. Not every web search engine works the same way, but most are crawler-based, meaning that they actively seek the web for pages to add to their index. The search engine is what you use to quickly lookup information from the index and display the results on the page. Search engines are the primary method for browsing the web, and there are many different kinds that are built for finding specific information. Within each search engine are often advanced search options that are used to focus your search better and help you find what you're looking for.
How a Search Engine Works
- Search engines automatically create website listings by using software, often called spiders or spiderbots, that "crawl" web pages. They follow a site's links to other pages and index the information in the process.
- The crawler bots behind the search engine scour the web not only by jumping from one link to the next but also by checking each site for a robots.txt file. This file contains a listing of which pages on the site a search engine should crawl. This is one way website owners can block a search engine from indexing a particular page.
- Software spiders return to pages that have already been crawled on a pretty regular basis to check for updates and changes, and everything they find goes back into the search engine database.
Using a Search Engine
Every search engine is different, but the common idea with all of them is to type something into a search box and wait for the results. Some search engines also have a reverse search option that lets you browse the web with something other than text, such as a sound clip or picture file. Many search engines include extra features beyond just a simple search box. They let you interact with the index using special text commands or buttons that can filter the results and remove items that aren't relevant to what you're looking for. For example, there are lots of advanced Google Search commands that can be used to get better search results from Google.