Yammer is a social networking service within the Office 365 suite of applications. There is a lot of overlap between Teams and Yammer but there is some key differences also. Most notably Yammer is targeted more towards organization-wide announcements and communication. Yammer is also designed as an open platform in that by default messages are visible to all users unless the groups are specifically made private by administrators of the system.
At this time the University only supports the use of Yammer for staff. Students are unable to join.
A good way of visualising where each app sits in relation to each other and the role they might play within your daily activities is the following diagram.
