Users can include tags in the body of the message to highlight interest in the thread to others following that tag.Users can also mention (@Mention) a particular user to get the attention of that user from the post or reply they are submitting.
Site feeds display posts and replies among the users of the group.
There are several types of activities in Share Point Server 2013.
These include the following: In Share Point Server 2013, the newsfeed (or just simply the feed) displays activity information to users. In Share Point Server 2013, a user's My Site has several feeds available from which to choose.
For example, if a particular user is a subject matter expert in a particular area, users might @Mention the user to get that user's attention and maybe a response to the current conversation.
Users can like a post or reply in the newsfeed as a way of giving public validation that a post or reply was useful to them.