The ROS Community level concepts are ROS resources that enable separate communities to exchange software and knowledge. These resources include:
Distributions: ROS distributions are collections of versioned stacks that you can install. ROS distributions play a similar role to Linux distributions. They make it easier to install a collection of software, and they also maintain consistent versions across a set of software.
Repositories: ROS relies on a federated network of code repositories, where different institutions can develop and release their own robot software components.
The ROS Wiki: The ROS Wiki is the main forum for documenting information about ROS. Anyone can sign up for an account and contribute their own documentation, provide corrections or updates, write tutorials, and more.
Mailing lists: The ROS user-mailing list is the primary communication channel about new updates to ROS as well as a forum to ask questions about the ROS software.