Any type of advertising that occurs on the internet is considered online advertising. Online advertising comes in many forms, including display advertising, search engine advertising, email advertising, social media advertising, content recommendations, mobile advertising (app advertising). There are many challenges that come with online advertising, such as ‘ad fatigue’, when people tire of seeing online ads, rendering them ineffective, and the increasing popularity of ad blockers, which prevent ads from appearing on the user’s device. According to recent stats, 11% of the online population worldwide is blocking internet ads.