Commit

A commit is the fundamental unit of change in a version control system such as Git: a snapshot of a project's files at a specific point in time, bundled with metadata like the author, a timestamp, and a message describing what changed. Rather than storing a full copy of every file, Git builds each commit from linked objects: a tree describing the directory structure and blobs holding the actual file contents, so the entire history can be reconstructed efficiently.

Every commit is identified by a unique cryptographic hash (traditionally a 40-character SHA-1 string, with SHA-256 support gradually rolling out) derived from its content, author, timestamp, and parent commit. Change anything, even one character in the message, and the hash changes completely, which is why the ID also works as a tamper-evident checksum. Because each commit points to its parent, the history forms a linked chain, a structure conceptually similar to blockchain, though the two are otherwise unrelated technologies.

In crypto development, commit history carries real weight for trust and security. Projects publish their source code on platforms like GitHub, and developers, auditors, and the community study the commit log to see exactly who changed what and when. This matters for spotting a suspicious edit to a smart contract, judging whether a protocol's client software is still actively maintained, or confirming that a disclosed vulnerability was actually patched. Many maintainers now cryptographically sign commits with GPG or SSH keys so GitHub can mark them "Verified," a persistent record that helps prevent impersonation in high-stakes repositories where a single malicious commit could put user funds at risk.