Flickering in A/B testing refers to the inconsistent and unpredictable changes in performance metrics between two versions of a website or app being tested simultaneously. This phenomenon occurs when users are randomly assigned to either version, resulting in a fluctuation of data and making it difficult to determine which version is truly more effective. Flickering can be caused by external factors such as user behavior or technical issues, and can significantly impact the accuracy and reliability of A/B test results. Proper monitoring and analysis of flickering is crucial in order to make informed decisions and draw meaningful conclusions from A/B testing.