After a pull request has been opened, you can review and discuss the set of proposed changes.
Commenting on the diff of a pull request
After you open a pull request in a repository, collaborators or team members can comment on the lines in its diff. Adding line comments is a great way to discuss questions about implementation, or provide feedback to the author.
Checking out pull requests locally
When someone sends you a pull request from a fork or branch of your repository, you may want to merge it locally to resolve a merge conflict or to test and verify the changes on your local computer before merging on GitHub.
