Social

Yammer
Why Yammer?
https://mspartner.microsoft.com/en/us/Blog/mpn/article/yammer-or-sharepoint-2013-social-which-should-i-use

http://www.portalsolutions.net/blog/the-last-word-on-sharepoint-2013-vs-yammer-with-christian-buckley-and-rick-hinton

http://www.microsofttrends.com/2015/04/13/yammer-conversations-vs-sharepoint-collaboration-sites/

http://social.technet.microsoft.com/wiki/contents/articles/18841.sharepoint-2013-integrate-yammer-with-sharepoint-for-social-feature-s.aspx