What is the green dot next to other users pictures?

Whenever you see a little green dot next to a picture of someone on the platform it means that this person is currently on the app. This doesn't necessarily tells you if the person is available as they could be communicating with someone else at that time but it gives you a clue that that the person might respond faster to you as they should more rapidly see your question, notification or call. In a way, the green dot indicates if the person is live on the app.