User blog comment:MisterWoodhouse/The future of Chat/@comment-5082092-20200806001338/@comment-5082092-20200806002727

Matrix is communication (chat) protocol: https://matrix.org

Reference client: https://element.io

To give a comparison, you can consider Matrix analagous to e-mail protocols, and something like Element is analogous to client for reading your e-mail. Since the protocol is open, there can be many clients and servers for it, and servers are federated, just like e-mail is. Meaning you don't need to be registered on the same server to use the network.