What Is A/B Testing and Optimization A/B Testing, also known as split testing, is a data-driven marketing method that compares two versions of a webpage, advertisement, or email to determine which one performs better. Instead of relying on intuition, businesses use real data to make decisions that directly impact performance, conversions, and profitability. With A/B Testing, marketers can test headlines, visuals, color schemes, buttons, CTAs (calls-to-action), and page layo