Source control terms, defined
Plain-English definitions for source control terms as they apply to Unreal Engine 5 development, from commits and locks to One File Per Actor and World Partition. No jargon unless it's the jargon you'll actually hear.
Audit log
A tamper-resistant record of every action on a source control system: commits, syncs, lock/unlock events, permission changes. Used by producers and compliance officers to answer 'who did what when.'
Binary file
A file stored in a non-text format: textures, audio, compiled code, Unreal .uasset, most FBX. Source control systems can version binary files but generally can't merge them, which is why locking matters.
Branch
A parallel line of development. In Git-style systems, branches are cheap and common. In game workflows with heavy binary assets, branches are used sparingly because merging binaries is impossible.
Commit
A snapshot of your project at a point in time, recorded with an author, a message, and a timestamp. Commits are the atomic unit of history. You can return to any commit later.
Depot (Perforce)
Perforce's term for the server-side storage of a project's files and history. Analogous to a 'repository' in Git. Administered via Perforce server tooling.
Dedup / deduplication
Storing identical content only once regardless of how many times it appears. USourceControl keeps every version independently rather than deduplicating storage, and instead saves bandwidth by only syncing files that actually changed.
Exclusive checkout
A synonym for file locking. You 'check out' a file exclusively, meaning only you can edit it until you check it back in.
File locking
Reserving a file so that only one person can edit it at a time. Essential for binary files that can't be merged: Unreal Blueprints, levels, materials, DCC source files.
Git
The dominant distributed version control system for software engineering. Excellent for text. Struggles with large binary files without extensions like Git LFS.
Git LFS
Git Large File Storage. An extension that stores large files outside the main Git repo, replacing them with 'pointer files.' Reduces repo bloat but adds configuration complexity and bandwidth costs.
Hash / checksum
A short fingerprint of a file's content. USourceControl uses SHA-256 to detect any change, even a single byte. Two files with the same SHA-256 are guaranteed to have identical content.
HLOD
Hierarchical Level of Detail. Generated proxy meshes that stand in for distant clusters of actors in an Unreal Engine world. Derived data, which makes versioning it a genuine choice.
LFS pointer file
A small text file that Git LFS uses to stand in for a real large file. If a client isn't LFS-aware, the pointer file gets committed instead of the real asset, a common source of silent data loss.
Merge conflict
When two parallel edits to the same file can't be automatically combined. For text, merges are often resolvable. For binary files, they're usually unresolvable and someone's work is lost, which is why locking matters.
Nanite
Unreal Engine 5's virtualized geometry system. Nanite meshes ship with full-detail source geometry instead of hand-authored LODs, which makes individual assets dramatically larger than their UE4 equivalents.
One File Per Actor (OFPA)
An Unreal Engine 5 feature that saves each actor's data into its own external file instead of into the level, so you no longer need to check out the level file to change an actor inside it.
Per-file history
A version timeline for a single file, independent of the broader commit graph. USourceControl lets you view every version of any file and restore to any prior state in one click.
Perforce
A centralized source control system (full name Perforce Helix Core) dominant in AAA game dev. Strong at large binary files and locking; weak at remote-team workflows and cost-effectiveness for small studios.
Pull / sync
Fetching changes from the server to your local copy. USourceControl's sync is incremental. It only transfers files that actually changed since your last sync.
Push / commit
Sending local changes up to the server, where teammates can pull them. In USourceControl, 'commit' both records the change and pushes it. There's no separate 'local commit' concept.
Repository
The general term for a versioned collection of files. USourceControl uses the term 'project' instead, which better matches how Unreal teams think. Structurally similar to a Git repo or Perforce depot.
Restore
Bringing a prior version of a file back as the current version. In USourceControl, one click from the file history view. History is preserved. Restoring an old version creates a new commit, not a rewrite.
SHA-256
A cryptographic hash function that produces a 256-bit fingerprint from any input. USourceControl uses it for file integrity verification.
Sync conflict
When your local version of a file differs from the server version and you need to decide which wins. Usually prevented by locking for binary files; for text files, USourceControl presents a clear resolution UI.
uasset (.uasset)
Unreal Engine's binary container format for assets: Blueprints, materials, meshes, textures, animations. Because .uasset files are binary, they cannot be merged, which drives the whole Unreal source control workflow.
umap (.umap)
Unreal Engine's level file format. Historically enormous and the classic collaboration bottleneck; in UE5 with One File Per Actor it shrinks to a shell holding grid and data layer settings.
Versioning
The practice of keeping every change to every file in a recoverable history. Source control systems do versioning automatically at every commit.
World Partition
Unreal Engine 5's automatic world streaming system. Replaces hand-authored sublevels with a spatial grid, and enables One File Per Actor by default, which is what makes real parallel work on one world possible.
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