Overview
Yammer gives you a way to connect and collaborate across your company as well as with external team members, customers, vendors, and so on. It is a way to ask questions, discuss and share ideas and solutions, and share updates.
In Yammer, documents can be discussed, edited, and co-authored via Office Web Apps and content in Yammer can be discussed and shared directly from Office 365 services such as SharePoint, Delve, Skype Meeting Broadcast, and more:
Yammer needs to be activated in Office 365. By default, Newsfeed is on instead of Yammer. Newsfeed is an enterprise social platform included in Office 365 and limited to Office 365 only, unlike Yammer, which can be used via Office 365 or can be signed up for outside of Office 365 as a separate service via https://www.yammer.com.
You can turn Yammer on via settings in the SharePoint admin center:
Administrating via Office 365
There are quite a few admin centers that you can reach via the Office 365 admin center.
