What Is A/B Testing?
Last updated July 7, 2026
What Is A/B Testing?
A/B testing is how you replace 'I think this headline is better' with 'this headline made us 18% more money.'
The short version
A/B testing (or split testing) is a method of comparing two versions of a webpage, email, ad or feature by showing each to a random segment of your audience and measuring which drives better results against a defined goal. It replaces opinion with evidence about what actually works.
How it works
You create two versions that differ in one element. Traffic is split randomly between them, and each version's performance is measured.
What's worth testing
Headlines and value propositions.
Calls to action , wording, placement, prominence.
Page structure and the order of information.
Form length and the fields you ask for.
Pricing presentation and offer framing.
How teams fool themselves
The classic error is stopping a test the moment one version pulls ahead. Early leads are usually noise.
Significance in plain English
Statistical significance means the result is unlikely to be down to chance. A common threshold is 95% confidence.
FAQ
What's the difference between A/B testing and multivariate testing?
A/B testing compares two whole versions, changing one thing. Multivariate testing changes several elements at once.
How long should an A/B test run?
Until it reaches your predetermined sample size and statistical significance.
Can you A/B test with low traffic?
Formally, not well.
Sources
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