Significance level is the value of statistical significance. It is the level of confidence (denoted by P) in the A/B test result that the difference between control and variation is not by chance. There are two accepted significance levels: 95% or 99% Significance level can also be expressed as the level of confidence in the A/B test result that the difference between control and variation is by chance. In that case there could be two accepted significance levels: 5% or 1%