Note: GitHub-hosted runners are not currently supported on GitHub Enterprise Server. You can see more information about planned future support on the GitHub public roadmap.
A GitHub-hosted runner is a virtual machine hosted by GitHub with the GitHub Actions runner application installed. GitHub offers runners with Linux, Windows, and macOS operating systems.
When you use a GitHub-hosted runner, machine maintenance and upgrades are taken care of for you. You can run workflows directly on the virtual machine or in a Docker container.
You can specify the runner type for each job in a workflow. Each job in a workflow executes in a fresh instance of the virtual machine. All steps in the job execute in the same instance of the virtual machine, allowing the actions in that job to share information using the filesystem.