This is a cloud-hosted service used to share and synchronize work among small teams. But it is also a great way to save your project on a remote server. Once enabled, every change made within your project is logged and compared to a remote copy. Simply hit the Publish Now button when your local changes are ready to be synced with the remote project directory. For details on Collaborate and the other Unity Services, visit https://unity3d.com/unity/features/collaborate.