Commit
One saved change to the code, with a unique ID (hash), an author and a message.
Definition
Builds are made from commits, so the commit hash is the most precise answer to "is this fix in my build?". Hashes are long but usually shown shortened to 7 characters.
In practice
Build 412 was made from commit 7f3d0b1, which includes the fix from a1c9e2f.
Learn it in context
Lessons that use this term.