SEM is Search Engine Marketing – which comprises of all marketing that can be related to a search engine, such as Google, Bing, Yahoo etc. This marketing relates to search (text ads), Google Shopping ads, Ads in Google Maps, the Google Display Network and YouTube. PPC is Pay Per Click – which is the traditional way of paying for a search ads campaign, you jump in to an auction and if someone clicks on your ad, you pay for that click. There are other ways to pay for your ads in SEM, like cost per 1000 Impressions (CPM), Cost per View (CPV) or even Cost per Conversion.