gh is GitHub's official CLI. It lives next to git, not inside it. Install via brew install gh, then gh auth login.
Daily commands:
gh pr create --fill # PR with title/body from commit
gh pr list # PRs in this repo
gh pr view 123 # open in pager
gh pr checkout 123 # check out a PR locally
gh pr review 123 --approve
gh pr merge 123 --squash
gh issue list --label bug
gh release create v1.0.0 --notes "..."
gh repo clone org/repo
gh repo fork --remote # fork + add remote
The killer feature: gh pr checkout works on any PR (even from forks) in one command. Reviewing locally becomes effortless.