One of the most common types of user testing is A/B testing. It allows you to compare the effectiveness and usability of two product versions and understand which is better.

A/B testing is generally done by randomly showing one of the two versions of the product to users without showing them the other version. It's essential to test only one design element at a time for the most accurate and usable results.

A/B testing provides objective and statistical — quantitative — data, but it doesn't explain users' behavior. That's why it's best suited for later stages of the design process or at the start of a redesign process. Typical use cases include refining color palettes or comparing how two images impact user behavior.