Git Blame: Track Changes Back to Their Author

What Git Blame Does

`git blame` annotates every line of a file with the commit hash, author, and date of the last modification. It answers: "Who changed this line, and when?"

git blame src/server.ts

Output:

abc1234 (Alice 2024-03-15) const API_URL = "https://api.example.com";

def5678 (Bob 2024-04-01) const timeout = 5000;

ghi9012 (Alice 2024-05-10) function fetchData() {

Practical Uses

**Find who introduced a bug:**

git blame src/auth.ts

# Find the line with the bug, note the commit hash

git show abc1234

**Understand why code exists:**

Sometimes the blame output points to a commit whose message explains the reasoning behind a seemingly odd line of code.

Useful Options

# Blame a specific range of lines

git blame -L 30,50 src/utils.ts

# Show the raw commit contents alongside blame

git blame -s src/config.ts

# Ignore whitespace changes

git blame -w src/styles.css

# Follow file renames

git blame -C src/refactored.ts

Blame Etiquette

**Blame finds responsibility, not fault.** A commit that introduced a bug was a best-effort change at the time. Use blame to understand and collaborate, not to assign blame in the accusatory sense.

Combining with Other Commands

# Blame + log for full context

git blame src/app.ts | grep "TODO"

git log --oneline -5 -- src/app.ts

`git blame` is a forensic tool for understanding the evolution of your codebase, one line at a time.