Rebase

Server-side rules that stop people from pushing straight to important branches, requiring reviews, passing checks, and intact history instead.

Copying the change from one commit onto another branch as a new commit, the standard way to backport a fix without merging everything else that came with it.

A recorded snapshot of a project with a message explaining it.

Cryptographically signing Git commits so a commit's author can be verified rather than merely claimed, the key types used, and what a green verified badge does and does not prove.

The Git state in which the current checkout points directly at a commit rather than a branch, harmless for looking around but a trap for new work, since commits made there belong to no branch and can quietly disappear.

The two basic ways Git joins branches, by sliding a branch pointer forward or by recording a new commit with two parents, and how the choice shapes a project's history.

A branch created to develop one change in isolation before merging it back, a workflow that keeps the main line stable but grows riskier the longer the branch lives, since its divergence from everyone else's work compounds.

Overwriting a remote branch with local history that doesn't contain it, the operation that makes rewritten history shareable and silently deletes other people's work when used carelessly.

Git's tool for rewriting a series of commits before sharing them, reordering, combining, splitting, and rewording them so the history tells a clear story rather than recording every false start.

Overlapping changes that a merge cannot combine automatically, requiring a decision.

Validating changes against the state they will actually merge into, in order, rather than in isolation.

Git's private record of everywhere HEAD and each branch has pointed, the safety net that makes a botched reset, rebase, or deleted branch recoverable for weeks.

Two changes that merge cleanly and are incompatible in meaning.

A chain of dependent changes, each reviewed separately and merged in order.

Combining two lines of work by comparing both against their common ancestor.