Yammer can be directly integrated into your Dynamics CRM instance. You just need to configure the connection to run the Yammer.
Yammer is an enterprise social network. The company was created in 2008 and was bought by Microsoft in 2012. This is a corporate-friendly social media network. Any user can join the network with a business e-mail account, as long as the company's domain is registered. Once you joined Yammer, you can create internal and external networks for employees, customers, suppliers, and so on.
The application structure is quite similar to that of Facebook when accessed online, outside Dynamics CRM. You have a news feed on the main page, and you have the ability to follow users as well as send and receive private messages.