Use @mentions to get someone's attention in Teams

An @mention is like a tap on the shoulder — a way to get someone's attention in a channel conversation or a chat. In the box where you type your message, type @, then type the first few letters of the person's name. You can also @mention entire teams and channels.

To get someone's attention in a channel conversation or a chat, @mention them. Just type @ before their name and then select them from the menu that appears.
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They receive a notification, which they can click to go directly into the point in the conversation where they were mentioned.
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To get the attention of an entire team:
•Type @team to message everyone on that team.
•Type @channel to notify everyone who has favorited that channel.