A/B Testing, also called split testing, compares two different versions of a web page against one another to determine which version performs better.
With A/B testing, one creates two different versions of an online instrument, such as an email, image, landing page, or ad, and tests one against the other through a campaign to observe which one gets a better response from its target audience.
A/B testing is used frequently in online marketing, during which one version is given to one specific group and the other version to a different group. One can then see how each variation performs. Just like any other competition, you are pitting two different versions of an asset against one another to see which one comes out superior.
Knowing which one works better can help make superior future decisions regarding email copies, web pages, etc.