Search Engine Optimisation
Search engine Optimisation (SEO) as a subset of search engine marketing seeks to improve the number and quality of visitors to a web site from "natural" ("organic" or "algorithmic") search results.
SEO is marketing by appealing first to machine algorithms to increase search engine relevance and secondly to human visitors. The term SEO can also refer to "search engine Optimisers", an industry of consultants who carry out Optimisation projects on behalf of clients.
SEO often requires making changes to the source code of a site, it is often most effective when incorporated into the initial development and design of a site, leading to the use of the term "Search Engine Friendly" to describe designs, menus, Content management systems and shopping carts that can be Optimised easily and effectively.
A range of strategies and techniques are employed in SEO, including changes to a site's code (referred to as "on page factors") and getting links from other sites (referred to as "off page factors").
Search Engine Marketing
Search engine marketing (SEM) is a set of marketing methods to increase the visibility of a website in search engine results pages (SERPs). The three main methods of SEM are:
Search engine Optimisation attempts to improve rankings for relevant keywords in search results by improving a web site's structure and content.
Pay per click advertising uses sponsored search engine listings to drive traffic to a web site. The advertiser bids for search terms, and the search engine ranks ads based on a competitive auction as well as other factors.
Paid inclusion can provide a guarantee that the website is included in the search engine's natural listings.