Yammer appeared as a "Twitter within your organisation" solution that was basically free for individuals to use. Staff would sign up their team, and then use it

Yammer appeared as a "Twitter within your organisation" solution that was basically free for individuals to use. Staff would sign up their team, and then use it like Twitter to keep their team up to date with whatever they were working on. The money comes in when a team member leaves... as individuals sign up, the company had no means to deny the individual access to these little spaces. So the company would purchase some plan or other, and be able to manage enterprise access. As someone who used Yammer in the early days, this felt like an extortion play. It was years before Microsoft purchased them, and somewhere around this time they had moved from short statuses to longer posts and various groups, files, etc... a real-time team collaboration space based around a stream of messages that started to look like "Facebook within your organisation". In many ways Yammer became what SharePoint should have been for the collaboration features. That's the v. brief history of Yammer.