The Multi-Account Containers extension for Firefox is a useful addition. I typically have a couple dozen tabs open at any given time, which clutters up the tab bar and makes it difficult to find a given tab. Categorizing the tabs into containers fixes this problem, with the ability to hide and show containers of tabs.

I didn't give a five-star rating to the Multi-Account Containers extension because there are some (in my opinion) missing features and functionality which I won't go into here, but one disappointment is that containers and their tabs are not saved to the 'cloud'. When I had my tabs and containers set up how I wanted them, I switched to an OS on another partition where I had Firefox installed. When I logged into Firefox, I was expecting my tabs and containers to sync with what I had set up in the other instance of Firefox and show up in this instance. They did not.