Ontohub ist organised in git repositories, which contain collections of ontologies. Each repository contains ontology files and other files. Git provides a version control, facilities for concurrent editing and merging in case that two people have edited the same document.
Ontohub page http://ontohub.org/repositories
This page provides an overview over and links to the public repositories that are currently available.
If you are logged into Onthohub, you can create your own repository by creating the "Create Repository" button.
Access permissions can be given per repository - all ontologies in a repository inherit its permissions.