What is A/B Testing?
Comparing two ad variations to determine which performs better.
Definition
A/B testing (split testing) is the practice of running two versions of an ad, landing page, or email simultaneously — changing a single variable like the headline, image, or CTA — and measuring which version drives more conversions. Statistical significance is key: you need enough impressions (typically 1,000+ per variant) before declaring a winner. The winning version becomes your new control, and you test the next variable. This iterative cycle is how top brands continuously improve performance.
Example
A supplement brand runs two identical ads but swaps the hero image: Version A uses a lifestyle photo, Version B uses a product flat-lay. After 5,000 impressions each, Version B has a 23% higher CTR, so the brand scales Version B and tests headline copy next.
Related Terms
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