You can migrate any existing standalone role into a collection and host the collection on Galaxy. With Ansible collections, you can distribute many roles in a single cohesive unit of re-usable automation. Inside a collection, you can share custom plugins across all roles in the collection instead of duplicating them in each role’s library/` directory.
You must migrate roles to collections if you want to distribute them as certified Ansible content.
Collections are a distribution format for Ansible content. You can use collections to package and distribute playbooks, roles, modules, and plugins. You can publish and use collections through Ansible Galaxy.