When two or more versions are shown to potential customers to see which will drive more sales.

Success with marketing is not made from what you think. It comes from what you know. 

Facts matter. Opinions don't. 

Getting to the facts is often only possible by A/B testing variations. This applies to all elements involved in your marketing campaign. Images, adcopy, landing pages, ect.

No matter how much you know about marketing, all humans have blind spots. And you may not know which elements will resonate best with potential customers at a certain point in time.

Assembling advertising from your swipe file and customer demographics can greatly reduce the A/B testing needed.

However, A/B testing needs to be run on all elements of your marketing campaign. Blind spots will be revealed and your efforts will become more profitable.