# Git Diff

URL: https://softwaredictionary.org/terms/git-diff
Category: Version Control
Last updated: 2026-09-30

In short: Git diff is a Git command that shows the exact line-by-line differences between two versions of your code, such as working files, staged changes, or commits.

## What is git diff?

`git diff` answers the question 'what exactly changed?'. It compares two versions of your files and prints only the lines that differ: lines starting with `-` were removed, lines starting with `+` were added, and a few unchanged lines around each change, called context, show where it happened. This format is called a unified diff, and it is the same view you see when reviewing a pull request.

What gets compared depends on the arguments. Plain `git diff` shows edits in your working directory that you haven't staged yet, `git diff --staged` shows what the next commit will contain, and `git diff main feature` compares the latest commits of two branches. You can also compare any two commits by hash, add a file path to limit the output to one file, or use `--stat` for a short summary of how many lines changed in each file.

A diff is like the track-changes view in a word processor, which shows deletions and insertions instead of the whole document. Developers run `git diff` before committing to double-check their work, code review tools display diffs so reviewers can focus on what's new, and the output can be saved as a patch file and applied elsewhere with `git apply`.

`git diff` is often confused with `git status` and `git log`. Status only lists which files have changed, log lists commits, and diff shows the actual lines inside the changes. A common surprise is that plain `git diff` shows nothing after `git add`: the changes are now staged, so you need `git diff --staged` to see them, and brand-new untracked files never appear in plain `git diff` at all.

## Key takeaways

- `git diff` shows line-by-line changes, with `-` for removed lines and `+` for added lines.
- Plain `git diff` shows unstaged changes; `git diff --staged` shows what will be committed.
- You can compare branches, commits, or single files, and `--stat` summarizes each file's changes.
- `git diff main...feature` shows what a branch changed since it split off, as a pull request does.
- Diffs are the basis of code review and of patch files that can be applied elsewhere.

## Example: Comparing changes with git diff

```bash
# Unstaged changes in your working directory
git diff

# Staged changes: what the next commit will contain
git diff --staged

# What a feature branch changed since it split from main
git diff main...feature/search --stat

# Sample output for one changed line:
# @@ -12,2 +12,2 @@ function total(items) {
#    const sum = items.reduce((a, b) => a + b, 0);
# -  return sum;
# +  return sum + tax;
```

## Frequently asked questions

**How do I see staged changes in Git?**

Run `git diff --staged`, or its older synonym `git diff --cached`. Plain `git diff` only shows changes that haven't been staged yet.

**How do I compare two branches in Git?**

Use `git diff branch-a branch-b` to compare their latest commits directly, or `git diff branch-a...branch-b` to see only what `branch-b` changed since it split off from `branch-a`. Add `--stat` for a per-file summary or `--name-only` to list just the file names.

**What do the plus and minus signs mean in a diff?**

Lines starting with `-` exist in the old version but not the new one, and lines starting with `+` exist only in the new version. A modified line appears as a removal followed by an addition, and lines starting with `@@` mark where each block of changes begins.

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Software Dictionary: https://softwaredictionary.org/ · https://softwaredictionary.org/llms.txt