When you create a project, a chat room specifically for that project is also created.
You can access the chat rooms from any page by clicking the chat icon at the top right in the header.
To tag people in a chat message (they will receive a notification), you can either type the @ symbol or, click the user icon to the right of the chat box. Select the user you would like to tag and they will receive a notification when you send the message.
Hold down "Ctrl" then press "Enter" to send the message to save you clicking the send button
Click the "pop out" button to pop the chat out into it's own window so you can carry on browsing to other pages whilst the chat stays open