Page rank or domain rank refers to the algorithm used by Google to measure a website’s authority. The details on what exactly determines this algorithm are unknown, however certain factors, such as the number and quality of inbound links, definitely play a part. The higher a website’s page rank, the more likely it is to be listed higher in search results.
Pay per click (PPC) is a form of online advertising that is used to direct traffic to a website, where the advertiser pays an ad publisher each time a user clicks on their ad and is directed to their site. The most common form of PPC advertising is on search engines (Google Adwords and Microsoft Bing dominate this market). In that case, ads are served to users based on the keyword or search query they have entered. There are many other sites where PPC advertising is used (Facebook, Instagram and LinkedIn to name a few). On these social sites, ads are shown to users based on selected audience targeting.