Also called significance or stat sig.

Measures the likelihood of incorrectly rejecting the null hypothesis when the null hypothesis is actually true. 

Achieving statistical significance means you've proven there's an effect, or an actual, true difference between the test versions.

When calling a result “statistically significant,” what you’re really saying is: the test achieved statistical significance level (α) based on a p-value of ≤0.05 at a +95% level of confidence that you don’t have a type I error.

The terminology and ideas behind significance can get complicated quickly.

However, as a digital marketer, it's important to know whether a result is valid -- and therefore statistically significant.