Search engine marketing (SEM) is a form of Internet marketing
At Search Engine Land, we commonly use SEM and/or “Paid Search” to refer to paid listings, with the long run of seeking to advertise used to embody each SEO and SEM.
1. Paid search ads
2. Paid search advertising
3. PPC (pay-per-click)
Pay Per Click Advertising in Google, Yahoo!, Bing/MSN, Gmail, YouTube, Linkedin, Facebook and etc.