In response to a query, a Search Engine displays a Search Engine Results Page (SERP). In this results page, in essence, is a list of websites which match the queried keyphrase (See on the right). We use the term “keyphrase” instead of “keyword” because this term is closer to what we mean : a keyphrase is made of several keywords.
On a SERP there are two kinds of results : the sponsored links (in blue on the picture) and the organic links.
The first ones are advertising and are paid for using the Pay per Click (PPC) model; the other ones are selected by Search Engines using their own criteria (algorithm). If your site is relevant to a search query, you will be included in the organic listings of a SERP.
It seems to be enough vocabulary for today. Try to assimilate all this, otherwise you will suffer during the reading of the next entries! Next time, I will go further into the known/supposed rules of the Search Engines algorithms.
For more information about all this strange jargon, have a look at the LG Dictionary, a very good glossary of Internet Marketing.