I signed up just to leave this review, lol: This add-on is absolutely wonderful and I can't even begin to imagine using Firefox without it. Being able to organize tabs into different groups is a game changer. And being able to easily switch between them makes research (for Linux, gaming, writing, entertainment) is simply wonderful. It's also easy to use, to move tabs around and to save and backup groups. It even saves ungrouped tabs for later. I love this!