You may need to send a message to one person rather than an entire group when communicating on a Discord channel. By tapping on a user's username, you are able to private message them. But if you wish to contact that person within the channel, that can also be done. To do so, just type the @ symbol before the username. Afterwards, the contact's name will appear in a list, and you can either select it from there or type it. Messages sent to a group will be highlighted in their name, indicating that they are specific to them.