Finally. Have made the switch over to Firefox a few months ago and this almost made me switch back. I swap context a lot at work / home so being able to group (and minimize said group) tabs helps a lot.
The Multi-Account Containers extension is great for this. Each container keeps its own context, so you can be logged in to the same service twice (or more) in tabs in one window. Can set it up so that some sites will always use a certain container, or that sites in a container will always use a proxy. That is EXTREMELY useful to me.
Helpful, but not what I'm looking for personally. I want to be logged into the same account, just have groups of tabs related to different tasks I'm working on. Could be documentation for various frameworks or tooling related to whichever language I'm working on. Chrome had this and it worked great.
Unfortunately, containers only isolate cookies and session data. It doesn't isolate history, bookmarks, saved logins, etc akin to Chrome's profiles. A major use of this is separating work and personal browsing.
Firefox technically has profiles as well (via about:profiles), but there's no profile switcher separate from an internal page.
Firefox has profiles, so you can further separate your work browsing from personal browsing. Each profile acts like a separate instance with it's own history, bookmarks, addons, everything...
No, and everyone keeps recommending extensions and hacky workarounds. Wish Mozilla would gets its head out of its ass and just add a damn button that runs the firefox -p [profile] command in the browser itself so we wouldn't need to use keep a desktop shortcut instead.
You can manage profiles from the About Profiles page when Firefox is open. If Firefox won't start or you need certain options, you can also start the Profile Manager when Firefox is closed.