Search engine marketing (SEM) is a form of Internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) primarily through paid advertising. Search engine optimization (SEO), which adjusts or rewrites website content and site architecture to achieve a higher ranking in search engine results pages to enhance pay per click (PPC) listings.
The concept behind Search Engine Marketing is quite simple: when a consumer or business person searches the Web through either a text box or by clicking through a directory hierarchy, he or she is in "hunt mode."
Marketers understand this "hunt mode" means that the searcher may very well be at the beginning, middle, or end stages of the buying cycle. When someone is researching a product or service to satisfy an immediate or future need they are in an unusual state: they desire relevant information and are open to digesting and acting on the information at their fingertips, all made possible by a search engine.
Search engine traffic is unique in the following ways
Search engine traffic is a non-intrusive method of marketing.
Search engine traffic originates from voluntary, audience-driven search behavior.
"Organic" search engine marketing (organic search listings) combines the best practices of creativity, technology, usability, copy, and online promotion / PR.
Some marketers believe that there are "tricks" that will improve the relevancy of sites within the search engines that are spider- (crawler-) based.