Search site: This Web site lets you search through some kind of index or directory of Web sites, or perhaps both an index and directory. (In some cases, search sites known as meta indexes allow you to search through multiple indices.) Google.com, AOL.com, and EarthLink.com are all search sites. DogPile.com and Mamma.com are meta-index search sites.

Search system: This organization possesses a combination of software, hardware, and people that indexes or categorizes Web sites — they build the index or directory you search through at a search site. The distinction is important, because a search site may not actually own a search index or directory.
For instance, Google is a search system — it displays results from the index that it creates for itself — but AOL.com and EarthLink.com aren’t. In fact, if you search at AOL.com or EarthLink. com and search, you actually get Google search results.

.Search results: Results are the information returned to you (the results of your search term) when you go to a search site and search for something. As just explained, in many cases the search results you see don't come from the search site you're using, but from some other search system.

Natural search results: A Web page can appear on a search-results page two ways: The search engine may place it on the page because the site owner paid to be there (pay-per-click ads), or it may pull the page out of its index because it thinks the page matches the search term well. These free placements are often known as natural search results; you'll also hear the term organic and sometimes even algorithmic.

Search engine optimization (SEO): Search engine optimization (also known as SEO) refers to “optimizing” Web sites and Web pages to rank well in the search engines.

Search term: This is the word, or words, that someone types into a search engine when looking for information