Split Testing (A/B Testing) –  a method of using online tools or platforms to conduct a controlled test over marketing variables – such as email subject lines, website headers, opt-in offers, landing pages, variations in copy, the color +/or text on a Call to Action button, ads, etc. Any time you pit two variations against each other and measure for clicks, completions, opt-ins, purchases or other desired action. Your base/original is the Control (A) and the version with slight variation is the Test (B). Don’t change too much between A and B or you won’t know what caused a difference in action.