You can now block merging pull requests until specified rules are met. Previously, you could only block merging a pull request through custom IAM permissions. You can now create an approval rule specifically for a pull request, or create approval rule templates to be applied to all future pull requests in a repository. You can specify rule requirements, such as the total number of approvals or approval from a specific user, that must be met before code is merged. Approval rules and approval rule templates help ensure that only high quality code changes are merged into your codebase.