Search engine registration is how a webmaster submits a web site directly to a search engine.
There are two basic reasons to submit a web site or web page to a search engine: The first reason would be to add an entirely new web site to the search engine. The second reason is to have a web page or web site updated in the respective search engine.
Most websites want to be listed in popular search engines, because that's how most people start their search for a product or service. A searcher, (or AKA "User"), seeks information on the web, using a search engine. Websites that appear on the first page of a search are, usually, called the "top 10".
Thus, webmasters often highly desire that their sites appear in the top 10 in a search engine search. This is because users are not very likely to look over more than one search engine results page (also known as SERPs). In order to obtain good placement on search results in the various engines, webmasters must optimize their web pages. The process is called search engine optimization. Many variables come into play, such as the placement and density of desirable keywords, the hierarchy structure of web pages employed in a web site (i.e.. How many clicks from the home page are required to access a particular web page?), and the number of web pages that link to a given web page. The Google search engine also uses a concept called page rank.
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 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.