The @mention functionality allows you to link a person, place or piece of content in the community. This functionality can be used in when collaborating. When @mentioning a person the user is sent a social interaction notification in their Inbox. Depending on their preferences they will also get an email about. When @mentioning a place it will be noted in the place’s activity stream.
To use @mention:
In a piece of content, a status update, or comment, type the “@” symbol (or click the “@” icon if it is available) and start typing a person’s name or the title of a place or piece of content you want to bring visibility to. A search dialog opens and suggests possible matches.
Use an underscore “_” as a space to search for names or titles with multiple words. For example @David_R would match the users with the first name David whose last names begin with “R.” Your picker will include documents, discussions, and places, as well as people. Keep typing to narrow the choices further.
Select the correct match from the list. The new link shows up in your content.