Search engine marketing or SEM is a type of web development technique which entails development of a web page in such a manner that it increases the visibility of the webpage on the result pages when a query is keyed in on a search engine. For this purpose search engine optimization techniques are used which helps the webpage to appear on the first or second page of the search results. However to improve visibility of webpage search engine companies can be paid this is called paid inclusion or paid placement in simple words these are the ads which appears with the results like google ads.