As you learn about improving brand visibility search, you may come across another term: SEM. While some marketers use this interchangeably with SEO, it’s important to understand the distinction: SEM stands for search engine marketing, and it refers to activities that earn placement in search engine results pages. This means that it’s an umbrella term that includes both SEO and PPC. So although SEO is a form of SEM, it’s not the only tactic involved.