What is A/B Testing?
A/B testing (also called split testing) is a controlled experiment in which two versions of a single marketing element — Version A (the control) and Version B (the variant) — are shown to different segments of an audience simultaneously to determine which version performs better against a defined metric.
Why It Matters
A/B testing removes guesswork from marketing decisions. Instead of debating which headline is better or which CTA color converts more, testing produces definitive data. Brands that systematically A/B test consistently improve conversion rates, CTR, and ROAS over time.
How It Works
A/B tests change only one variable at a time to isolate what’s causing the performance difference. Variables commonly tested include email subject lines, ad headlines, CTA button text and color, landing page headlines, image choices, pricing displays, and form lengths. Traffic is split evenly between the two versions until a statistically significant winner is determined. Tools like Google Optimize, Optimizely, VWO, and native testing features in Meta Ads and Klaviyo make A/B testing accessible.
Real-World Example
Digital Media Run tests two versions of an email campaign: Subject line A: ‘How to Grow on Amazon in 2025’ vs. Subject line B: ‘The Exact Strategy We Used to Double a Client’s Amazon Sales.’ Version B achieves a 48% open rate vs. Version A’s 22%. The more specific, story-driven subject line is decisively better.
