Search Engine Marketing (SEM) is a term used to describe the process of advertising on search engines. Specifically, SEM campaigns refer to the sponsored links that are located in a dedicated area on the search engine results page, highlighted on the diagram below.
Often referred to as pay-per-click/cost-per-click campaigns, SEM marketing involves a bidding process, to ensure that your advertisement appears in a favourable position in search engine results when a particular keyword is searched. SEM provides a powerful means of advertising, in that you are able to advertise for free, and only pay when your advertisement is selected.