GitHub supports special closing keywords that connect a pull request to an issue and automatically close the issue when the pull request is merged into the default branch. Examples include keywords such as "fixes," "closes," or "resolves," followed by the issue number. Using a reference like Fixes #42 in the pull request description tells GitHub that the pull request resolves that issue. Assigning the issue to the pull request author does not create automatic closure behavior. Mentioning the issue after merging may create a reference, but it does not automatically close the issue retroactively. Adding the issue number to the pull request title may help humans understand the relationship, but the supported automatic closing behavior depends on the keyword reference.