A/B or split testing has been the standard way to optimize marketing campaigns for years. Google first ran an A/B test in 2000 to identify the optimum number of searches to display on its result pages. Today A/B testing is common practice in many different digital marketing channels including display ads, landing pages, email marketing, and pretty much anywhere that copy, images, or placement can be adjusted. A basic example of A/B testing would be splitting visitors to a website into two groups (A and B) and showing each group a slightly different version of the homepage. Everything else might be the same on the page apart from the header image.