Well, it depends who you ask. Search engine marketing (SEM) appears to be difficult to correctly define. Some even say it covers much broader spectrum that is still evolving and that causes it to be difficult to define. But many including the online dictionary Wikipedia agree that SEM includes search engine optimization (SEO), pay-per-click (PPC) and social media marketing (SMM), and it is a comprehensive approach to increasing visibility of websites in search results. In other words, SEM is marketing to Internet users through natural as well as paid advertising. Some say in addition to search engine optimization, SEM methods include paid placement, organic growth, contextual advertising, paid inclusion and digital asset optimization.
Even though many cannot agree on a definition of SEM, two most important search engines, Google and Bing, promote SEM as a combination of both paid and organic. But their actions obviously tilted towards paid advertising. In 2012, more than $19 billion spent in North America for SEM. The largest vendors of SEM include Google AdWords, Bing Ads, and Baidu. SEM now far outruns traditional advertising methods and businesses can manage their advertising campaigns through SEM vendors or use a SEM tool provider.