SEM means Search Engine Marketing
It is internet marketing, where we can promote our product/brand on social media. In this everyone will be working on paid marketing for the cause to get their website on the top page of the SERP (Search Engine Results Page). One thing is to get on the top of the page we have to write the good SEO, it means organically we have to write the content more and more until we reach the top of the SERP. The other way is to do paid marketing on behalf of organic or paid marketing we have to do good keyword research and then we need to create a campaign.