“SEM” is short for “Search Engine Marketing
refers to all the ways a website is promoted in order to gain more traffic from search engines. It can include organic search engine optimization, or paid advertising through Pay Per Click (PPC) ads like Google’s Adwords.

Most online purchases and first interactions with a business start with a search, usually with Google. Whether it is the unpaid organic search results or the ever-expanding Adwords search network ads, if you want to do business online, you need to show up when people search for what you do or sell.