Simply put, you show one version (A – original /old) to some visitors of your site and another to some (B – New). Not necessarily 50/50. If you have enough visitors and you want to play it safe, you may get a quick solid result by showing the (B) version to just 10% of visitors.
A – Original
B – New
Why do it?
You might have a good eye for design, but you might be surprised what turns a browser into a buyer sometime. You just don’t know.
What to think about
– Don’t change more than one thing at a time. What made a difference? I dunno?
– Have the patience to get a significant result – let the test take its time
– Think about what you want to achieve with the testing – before you start to test