What is a search engine?
A search engine is a database that has been created to search for Internet pages. Search engines allow an individual to enter a search term or terms and the engine attempts to match the request with Web pages. The results are displayed with links so one may access his/her choice directly.
When should I use a directory
/ portal or search engine? Use a subject directory if you have a broad
topic or you want to browse a list of recommended sites.
Use a search engine if you have a narrow or specific subject in mind or you want to search for particular types of documents. More on this topic
How do "search engines" search
Searching on the Internet is not done by humans but by programs called "spiders" or "robots." These programs are designed to go out into the World Wide Web and locate web pages, follow the links they offer, and take the information and add it to an index database. Webpage editors or professional webpage developers sometimes provide information about their pages as well. Most spiders return to the sites on a regular basis to look for changes or updates.
Each search engine programs its spider differently so that no two spiders conduct a search the same. Therefore, the results you’ll get will vary from engine to engine. For example, some spiders search for titles of web pages only, others look for particular words, or lines of text, still others reference every single word of a document. More on this topic