We provide two types of channels through our chat API: 1) Open Chat Channels (public chat rooms) and 2) Messaging Channels (private messaging and group messaging), and you will be able to test out both features on the sample website.
The sample website's source code is open-sourced, so feel free to check it out and play around with it. The sample app's code comes with the both examples of Open Chat Channels and Messaging Channels using the chat API.
You can use open chat channels to create public chat rooms for community apps and games. Think of it like Slack's channels or Battle.net for games. These kind of channels function as a chat room where people can join as they wish. You can hide them from the list to make it look private for certain use cases.
You can create as many channels as you want if you want to partition your users since having too many people chatting at once will make it literally impossible to read. So if you have plans to build something like Twitch.tv with hundreds of thousands of concurrent users, you should definitely consider partitioning for these kind of open chat rooms.
Please note that even though the demo website is using full-screen, it does not mean chat rooms can only be made this way: You can modify it to function in a widget-like form for your website, similar to Facebook messenger on your desktop or Olark.
If you are not building something like Slack, widget-like user interface will help your users focus on the core content of the website while still being able to engage the conversations with other users on your app. This is also true for web-based games.
Let us know if you have any questions or feedbacks while using our chat API or the sample website. :)