Conversion rate optimization is the practice of increasing the share of visitors who take the action you care about, such as buying, booking a demo or signing up. A/B testing is the main tool to prove that a change caused an improvement instead of guessing. This hub covers both: how to find problems with analytics, heatmaps and session recordings, how to write a hypothesis, how to calculate sample size and statistical significance, and how to run tests on landing pages, forms and checkout flows. It also covers testing inside ad platforms, such as ad copy and creative experiments, because landing page tests and ad tests affect each other. The articles use plain language for the statistics and link to primary sources for the formulas. Many sites do not have enough traffic for classic A/B tests, so you will also find guidance on what to do when a test cannot reach significance in a reasonable time.
Conversion rate optimization (CRO) is the process of increasing the share of visitors who take the action you want, such as a demo request or a purchase. You do it by measuring where people drop off, finding out why, and fixing or testing the pages that matter most.
Conversion rate optimization (CRO) is the process of increasing the share of visitors who take the action you want, such as a demo request or a purchase. You do it by measuring where people drop off, finding out why, and fixing or testing the pages that matter most.
Updated October 1, 2026 · 7 min read