Discord is a messaging application that allows you to speak real-time via text or voice. Personally, I would say it is the best one available, because some of the features it offers are: – Guilds (communities of people, maximum 800,000 members) that you can customize and control with roles, permissions, etc.
https://www.reddit.com/r/discordapp/comments/oxtee9/what_is_discord/

