Social Activities - Google Analytics

Overview

Today it is often the case that engagement with content — e.g. sharing, comments, likes, votes, etc. — doesn’t always take place on the website from which the content originates. Instead, in many instances these activities take place "off-site" on various social networks, unbeknownst to the author. Google Analytics allows you to track and gain insight into the off-site social activities related to the content on your website.

What is a social activity?

A social activity represents a social action (e.g. +1, comment, vote, share, etc.) that references content on your website but does not originate from your website. Instead, the social action originates off-site, on a social network. Social activities also include additional metadata related to the action, such as: the social network, user, time, photo, comments, etc.
Example: Social activity on Google+

The aggregation of social activities related to a particular piece of content or a website is referred to as an activity stream.

 

https://developers.google.com/analytics/devguides/platform/social-activities