Search Engine Marketing is most commonly called:

PPC (Pay-Per-Click) is the most common term for Search Engine Marketing (SEM). While SEM encompasses both paid advertising and organic search optimization, in practice, when people refer to SEM, they are usually talking about paid search campaigns, which operate on a PPC model. SEO (Search Engine Optimization) specifically refers to the strategies used to improve organic search rankings, not paid advertising. Digital Marketing is a broad term that includes all online marketing efforts, of which SEM is just one component.