[dewey]

I'd group them in two big segments.

1) Sales chat

2) Support chat

Both of them I prefer over emailing, calling or writing into some contact box and receive an answer days later. Live chat windows are in almost 100% of the cases I've interacted with them quicker, as they tell you if someone is online and how many minutes you are expected to wait.

Sometimes 1) can be spammy when they make sounds or open automatically but I still prefer to ask a quick product question before signing up for something via the chat than emailing someone.