Paid search engine results page advertising (SERP). Paid search is another term for this. SEM advertising are used to increase traffic to websites, but they can also include other calls to action, such as making a phone call or visiting a nearby store. SEM advertising are triggered by keywords in a search query. They are normally seen near the top of search results, although they can also be found on the side. The majority of SEM is pay-per-click (PPC), which means you only pay when someone clicks on your ad.