Search Engine Terminology

Inbound Links	Hyperlinks from other websites to yours. Also known as return links or backlinks.
Page Rank (PR)	Page Rank. A number between 0 and 10 given by Google to every page on the internet as a rating of how popular the page is.
Reciprocal Links	Links between two websites - each webmaster agrees to provide a link to the other website so both will benefit.
Robot / Spider	An automated piece of software which travels around the internet looking for web pages and storing them in the search index. Robots are good - you want them to visit as often as possible.
Search Algorithm	The "equation" used by a search engine to decide which web pages are the best match for a search term.
Search Index	The database of web pages used by a search engine. When you perform a search, the search engine looks in this database to find the best matches.
SEO	(1) Search Engine optimization - The process of optimizing. (2) Search Engine optimizer - A person who offers optimization as a commercial service.
SERP	Search Engine Result Page, i.e. the list of web pages shown when you perform a search.