Microsoft Teams and Channels for Office 365
Channels are a great and innovative feature in Microsoft Teams. Channels minimize silos within team communication as well as improve transparency, they can also be accessed using applications on smartphones. It is almost like a dedicated communication for members of a team. All channels share same security as the team, but private channels (with unique security) could be there in not too distant future.
Source: Microsoft.com
By default, each Team has one Channel called General. But additional channels can be created.