Containers are one of the best features Firefox has gained in recent years. They make managing multiple website accounts so much easier than trying to use multiple browsers or browser profiles. They are also useful for developers in lots of ways.

I don’t know why Mozilla doesn’t promote Containers more, they can’t even be used out of the box because they have to be enabled with an extension. It’s a far better feature than many of the other recent gimmicks like time limited colour schemes.