is awesome and you should use it is a great way to start using crypto and associate your public key with your identity. Albeit, you don't want to upload your private key, which is something they provide. It's like a crypto social network, so if I want to send you an encrypted message, I can lookup your public key by your twitter handle, github username, etc.

Anyways, more people should use it. I have quite a few invites available, so if you want one, shoot me a message. My keybase page is here.