Search engine marketing (SEM) and its uses

Search engine marketing (SEM) means an internet marketing to make website publicity in the search engine results page in sponsored listings. Sponsored listings means by spending money to place a website in search engine results page (SERP). Search engine marketing (SEM) also depends on contextual advertising it means showing the ads by related content. In SEM it has to spend money to promote a website, where as in Search Engine Optimization (SEO) there is no need to spend, however the listings of SEO can be seen in SERP as a non-sponsored listings name as Organic Search or Organic listings.