The spiders will try to search all the pages on the web regardless of being submitted to the search engines or not. The spider returns to the web site on a monthly or bimonthly basis to look for changes in the site. Everything the spider reads is categorized into the second part of a search engine, the index. The index is a giant database containing a copy of every web page the spider finds. If a web page changes, the index is updated with the new information once the spider revisits the site.
Search software is the third component of a search engine.
This is the application program that sifts through the millions of recorded pages to find matches to a search query, then ranks them in order of what it believes to be the most relevant. There are two main types of search engines scouring the web today, Deep Search Engines and Standard Search Engines. Deep search engines are constantly searching the World Wide Web for new and updated pages. These search engines are useful when searching for obscure and hard to find information. By searching for popular subjects like entertainment and games the number of results returned would be in the millions, making it extremely difficult to find exactly what you're looking for.