Everyone in your company can work together like never before on Chatter–even colleagues who don't have a Salesforce license. With Chatter invites, collaboration at your company is private, secure, and free.
Invite co-workers who are not currently using Salesforce to collaborate on projects, files, and more. You can send invites from Chatter Central or the people tab.
When someone accepts a Chatter invite, he’ll receive his own Chatter Free license. Now even non-Salesforce users in your company can complete their own profiles, post status updates, follow co-workers, create groups, post files, and collaborate with their colleagues.