Search Engine Marketing (SEM) is a type of internet marketing where websites or business are promoted mainly through paid advertising to gain visibility and rank higher on search engine results pages (SERP). SEM is an effective medium for placing advertisements in front of the audience when they search for something on the internet. And, chances of conversion are much more through Search Engine Marketing.
SEM and SEO (Search Engine Optimisation) are both similar in terms of their goal. Both work on gaining visibility to a website. However, SEM is about paid marketing and SEO is not. SEO is about optimising a website by modifying the content in it or by altering the architecture of the website to get higher ranking on SERP. In SEO, businesses do not pay Google to bring traffic or if the audience visits their page. Whereas in SEM, businesses pay Google to place their advertisements on search engine results pages.