About milestones→
You can use milestones to track progress on groups of issues or pull requests in a repository.
Creating and editing milestones for issues and pull requests→
You can create a milestone to track progress on groups of issues or pull requests in a repository.
Associating milestones with issues and pull requests→
You can associate similar issues and pull requests with a milestone to better track their progress.
Filtering issues and pull requests by milestone→
Issues and pull requests can be filtered based on the milestone they're associated with. Once you've associated an issue or pull request with a milestone, you can find items based on their milestones. Within a milestone, you can prioritize issues and pull requests.
Viewing your milestone's progress→
In order to track your milestones, you'll want to get a better understanding of how many open issues and pull requests are remaining.