What is Diff?
Diff refers to the process of identifying differences between two sets of data or the output of a tool that displays these changes.
It is an essential technology in software development, allowing developers to compare “before” and “after” states to see exactly which lines were added, removed, or modified.
Common Diff Display Formats
Depending on the tool, diffs are usually shown in one of two ways:
- Unified Diff: Shows the changes along with a few surrounding lines (context). This is standard for patch files.
- Side-by-Side: Places the old and new data next to each other. This is visually intuitive and ideal for code reviews.
What Do the ”+” and ”-” Symbols Mean?
- Red Background / - (Minus): Lines that were removed or the state before the change.
- Green Background / + (Plus): Lines that were added or the state after the change.
Use Cases in Development
- Code Review: Focusing only on modified parts when reviewing Pull Requests in Git.
- Configuration Management: Comparing backup configuration files with the current state to find unintended changes.
- Log Analysis: Identifying the cause of errors by comparing “healthy” logs with “error” logs.
Compare Diffs on DevToolKits
Our Text Diff Comparison Tool lets you paste two blocks of text and see highlighted differences instantly in your browser.
Since it runs entirely in your browser (locally), you can safely compare sensitive data without ever sending it to a server.
💡 Tip: Sometimes text looks identical but shows a difference due to whitespace (spaces vs. tabs) or different line endings (LF vs. CRLF). Use trimming options to normalize your data for a cleaner comparison.