A/B Testing (also known as split testing) is a method of comparing two versions of a design or interface to see which one performs better. Typically, one variable is changed between Version A and Version B (such as the color of a Call to Action (CTA) button) while keeping all other elements the same. Real users are randomly shown either version, and their behavior (like click-through rate or conversion rate) is measured. The version that yields better user engagement or conversions indicates which design choice more effectively meets user needs.