What is Watchman?

I get this in Ember-CLI 0.1.3 : Could not find watchman, falling back to NodeWatcher for file system events I am on a windows machine. What is watchman? Do I install it manualy?

Watchman does not support Windows at the moment.

You can review the website for more details at: Watchman A file watching service | Watchman

Thanks! Can Ember-CLI detect it is on windows and remove the message and for now is there a way to remove the message manually?