A CL is a "Changelist". The terminology comes from the Perforce version control software.
Technically analogous to a "commit" in git.
The CL terminology stuck within Google even when the underlying version control system is not perforce. For example the Gerrit code review system also calls them "change lists".
It's the unit of granularity for code reviews at Google. In that respect it's analogous to a Pull Request or Merge Request in the outside world.
CL are meant to be updated (edited) in place during the code review process. This is something some people would also do with git commits (amending commits and force pushing) while others would add many individual commits to address code review issues (That's why PR is a better analogy).
The CL terminology stuck within Google even when the underlying version control system is not perforce. For example the Gerrit code review system also calls them "change lists".
It's the unit of granularity for code reviews at Google. In that respect it's analogous to a Pull Request or Merge Request in the outside world.
CL are meant to be updated (edited) in place during the code review process. This is something some people would also do with git commits (amending commits and force pushing) while others would add many individual commits to address code review issues (That's why PR is a better analogy).