Search Engines' Databases
There are many specialized searchable databases, accessible by the World Wide Web to access through a search box in a web page (for example, the UCB Library Catalog Pathfinder, or any other library catalog; or some statistics databases searchable on the web). The terms used in the search are sent into that specialized database, and are returned to in another web page that is dynamically generated for answer.
Databases provide the content storage for many sites, which dynamically create web pages around them, including ecommerce catalog sites, online news, and even entertainment sites. These databases generally have their own search functions, which may appear to take the place of a full-text search engine.
Once the search engine finds a new site, it uses a crawler program to retrieve and index the pages on the site. Pages can only be found when linked to with visible hyperlinks. For instance, some search engines are starting to read links created by Flash (for example, Google).
Search engine crawlers may look at a number of different factors when crawling a site, and many pages from a site may not be indexed by the search engines until they gain more PageRank, links or traffic. Distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled, as well as other importance metrics.
Google offers submission program, such as Sitemaps, for which an XML type feed can be created and submitted. A simple link from a site already indexed will get the search engines to visit a new site and begin spidering its contents. It can take a few days or even weeks from the acquisition of a link from such a site for all the main search engine spiders to begin indexing a new site, and there is usually not much that can be done to speed up this process.
A few search engines, such as Yahoo!, offers a paid submission service that guarantee crawling for either a set fee or CPC. Such programs usually guarantee inclusion in the database, but does not guarantee specific ranking within the search results.