You are on the Google+ stream page and you read content(s) shared by others. When you find it interesting or want to say something about it, you write a comment to share your thoughts.
Traditional forums or other commenting systems support nested comments and replies. So, when you want to reply to a particular commenter, you choose reply just next to that particular comment and reply to him – very straight forward, right?. But unfortunately Google+ doesn’t support nested comments or replies. This is not a big problem when a post has just few comments, but definitely a huge problem as more comments start to come in. Also note that one big problem with nested comments is it can get really messy and get too deep.
Interestingly Google+ solves the problem of reply, nested comments or discussions in a whole new and easy way (in a simple flat view but you can still achieve the same result). It’s called as mentions in Google+. (When you find +name or +pagename anywhere in a post or within a comment, that exactly what we are talking about).
Let’s walk through and explain this with a simple example (refer image)
In this example, Google+ news has shared a news about multiple admins, page analytics and ownership of pages from this site on Google+ news page. +Jason Proper, a Google+ user has commented on this post and if you notice our reply we have added +Jason Proper in the comment. This is know as mention in Google+ and serves as reply to a post or comment. The good news is when you mention someone that person get’s notified through Google+ notifications, in this case +Jason Proper will be notified (You are directly talking to whoever you are referring through mentions). You can even mention more than one person or page at the same time within a single post or comment.
This gives great flexibility without the hassle of nested comments. Just type + followed by name or page name, as you type Google+ will show you suggestions of users or page names. Once you select, it’ll appear within the post or comment. Using mentions you should be able to achieve the same functionality of replies and discussions as in any other traditional forums or commenting system.