Yammer is an internal community forum for your organization. Think of it like a Facebook or LinkedIn page just for employees! Yammer allows you to connect altogether for organization wide news and activities. Employees can post and connect socially.
Disclaimers: Not all applications may come with your current Microsoft license. Some applications are additional add-ins. Applications may be restricted and/or non-accessible per your organization. Any use of an application must follow your organization's data and usage policy. Contact your organization's management for more information.