A/B testing, also known as split testing, is a method of comparing two versions of a website, app, or marketing campaign to determine which one performs better. In A/B testing, two variations (A and B) are presented to users at random, with each variation differing in only one aspect. This could be the colour of a button or the wording of a headline. The results of each variation are then compared, typically using metrics such as conversion rate, click-through rate or engagement rate. These metrics help determine which version is more effective in achieving the goal that was set for the design.

A/B testing is commonly used in digital marketing to optimise website or app design, improve e-mail campaigns and test different ad formats and messages. By testing variations in a controlled environment, A/B testing allows to make data-driven decisions and improve the effectiveness of marketing efforts.