Reading a line diff

Understand additions, deletions and unchanged context.

Follow the signs

A plus marks a new line; a minus marks a removed line. Unmarked lines are shared context. A replacement appears as a removal and an addition.

Check the edges

Blank lines and whitespace are significant. Windows and Unix line endings are normalized. A trailing newline is visible as a final empty line.

The two number columns track each version independently. Deleting a line advances only the original number; adding one advances only the revised number. Symbols carry the meaning even without color.