Synonyms: split testing, bucket testing
In order to optimize a website page, A/B Testing, otherwise known as split testing is used to test different versions of the same content, where the original is set as a control against which a secondary version or challenger is compared. It is not limited to website pages, but also applies to on-site messages and advertising. By comparing the performance of the two different versions of the same webpage, or content within the webpage you can establish which version performs better.
Typically a conversion rate optimization platform is used for AB testing (such as OptiMonk).