Lets see if I can sum up the key areas of a search engine:
1) A user enters a key word or key phrase
2) The "search engine" then "returns a result set" of "links" that the search engine "thinks" is "most relevant" to the key word or phrase
Now, that was easy, I will now try to explain the meanings of the words in quotes
"search engine"- obviously there are the main 3 (google, yahoo, msn), but a search engine is an application that has a simple front-end interface and a HUGE database of words and websites.
"returns a result set"- is a list of websites ranked in order based upon the search engine's "algorithm"
"algorithm"- each search engine has its own special code or algorithm that sorts or ranks the database full of websites. Needless to say, the algorithm is VERY, VERY complex. Its made of thousands and thousands of variables that determine the sort order for key words entered into the search engine.
"links"- basically each link is a website that has been indexed or spidered or inserted into the search engine's database
"thinks"- the search engine's brains, if you will, is the algorithm. It has rules and values that help determine the sort order of listing a result set.
"most relevant"- again, determined by the algorithm, the search engine's job is to give you a list of websites IT THINKS is what you want. Sometimes it works. Sometimes the search engine fails to return to the user, what the user is looking for.
hope that helps!