What is an Google A/B test? A/B experiment allows you to test the performance of two (or more!) entirely different versions of a page. Start with your original test page -- the page whose content you want to test -- then create alternate versions of that page. You can change the content of a page, alter the look and feel, or move around the layout of your alternate pages -- whatever you choose. We'll vary traffic to your original page and your alternate versions, to see what users respond to best.
A/B experiments are the simpler version of testing with Website Optimizer. If you have a low amount of traffic and want results fast, creating an A/B test may be the right place to start.