A/B tests and other customizations mean that the content on a website depends on the visitor who's viewing it. These customizations are usually implemented through a dedicated A/B testing service, in order to let marketing teams run tests without having to get developers involved. The visitor's browser first downloads the page with default content, then the browser loads the list of customizations from the A/B testing service, and finally applies them to the page. However, these customizations introduce flicker. The visitor first sees the default content, and then the content disappears and is replaced. An anti-flicker snippet is a piece of code that prevents flicker by hiding the original page content until the customizations have been applied.