What is A-B Testing?

Running two or more variations of an ad simultaneously, such as comparing an image ad to a video ad or testing different thumbnails, to determine which version drives better results.

From Facebook Ads vs. Google AdWords: Which one should you be using? Part 2 #447

Running split tests with several variations of a landing page to determine which version performs better, used to improve or diagnose campaign results.

From Landing Page Optimization Tips - #seopodcast 220

Testing two versions of a page element such as color, copy, or positioning against each other to measure which one produces better conversion results.

From Customer Conversion Rate Tips - #SEOpodcast 266

Running two different ads, landing pages, or other campaign elements simultaneously over a set period, such as 30 to 40 days, to determine which performs better before adopting one as the standard.

From Google AdWords Do and Donts - Internet Marketing Podcast Number 207

Comparing two versions of a page or content element with numbers before and after to determine which version produces better results.

From Creating Content That Converts Customers - seopodcast 188