PageRank
PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at considerably more than the sheer volume of votes, or links a web page receives; for example, it also analyzes the page that casts the vote. Votes cast by pages that are themselves important weigh more heavily and help to make other pages important. Using these and other factors, Google provides its views on pages' relative importance.
Web Development
Web Development is a broad term and is at times confused with web design but should never be mistaken as such. Web Development includes any activity related to development of a web site for the Web or an internet. This can include e-commerce business development, web design, web content development, client-side/server-side scripting (e.g. PHP, JavaScript etc.), and web server configuration. However, among web professionals, web development usually refers to the non-design aspects of building web sites, e.g. writing markup and coding. Web development can range from developing the simplest static single page of plain text to the most complex web-based internet applications, electronic businesses, or social network services. Web development teams can span over hundreds of people (web developers) for larger businesses or can be as little as a single webmaster. Web development is more of a collaborative effort among different departments rather than then single effort of a designated department.