It's also got basic wiki type stuff, and some other features.
IRC is like USENET: It has barely evolved for decades, nobody can profit by improving the protocol as it's a commons, so it just stagnates and dies out.
Eventually all the decentralised protocols that were born in the early days of the internet will be gone.
The IRC protocol is in a different situation to USENET, because the latter has many different independent, individually federated networks of servers, whereas the latter has just one.
This means that server-side innovations can and do happen - they just need to respect the basic server-client protocol. Often the newer features are delivered through "services", which means they're in-band signalled.
Not entirely. Team control is a major part of it for companies, and history makes a huge difference to the experience. Slack servers allow the use of IRC clients, but I gave up on Colloquy almost immediately after seeing the benefits of history. For the right teams, the IRC+history combo can almost completely eliminate email use.
Also, Slack bought a company which did voice, video, and screen sharing. Since join.me went downhill, this will be a welcome addition to Slack.
Really? I wondered what all the hype about Slack was.
So, Slack is basically Colloquy, but for Windows morons and Linux weenies.
That's depressing.