Search engine marketing (SEM) is a another form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) through optimization and pay per click (PPC) advertising.
It is the process of gaining traffic and visibility from search engines through both paid and unpaid optimizing efforts.
The most common advertising techniques also used to refer to SEM activities are as follows:
PPC (Pay per Click)
CPC (Cost Per Click)
CPM (Cost Per thousand Impression)
CPA (Cost Per Action)
Paid search advertising