By using the possibilities of a graphical color display KDiff3 shows exactly what the difference is. When you have to do many code-reviews, you will like this.
Spaces and tabs that differ appear visibly. When lines differ only in the amount of white space this can be seen at one look in the summary column on the left side. (No more worries when people change the indentation.)
Analyze three files and see where they differ.
The left/middle/right windows are named A/B/C and have the blue/green/magenta color respectively.
If one file is the same and one file is different on a line then the color shows which file is different. The red color means that both other files are different.
KDiff3 can be used to merge two or three input files and automatically merges as much as possible. The result is presented in an editable window where most conflicts can be solved with a single mouseclick: Select the respective buttons at the A/ B/C windows to select the source that should be used. You can also select more than one source. Since this output window is an editor even conflicts which need further corrections can be solved here without requiring another tool.
Fast navigation via buttons.
A mouse-click into a summary column sync's all windows to show the same position.
Select and copy from any window and paste into the merge result window.
Overview column that shows where the changes and conflicts are.
The colors are adjustable to your specific preferences.
Adjustable Tab size.
Option to insert spaces instead of tabs.
Open files comfortably via dialog or specify files on the command line.
Search for strings in all text windows with → (Ctrl+F) and → (F3) menu items.
Show the line numbers for each line.
Paste clipboard or drag text into a diff input window.
Network transparency via KIO.
Can be used as diff-viewer from the KDevelop 3.
Word-wrap for long lines.
Support for Unicode, UTF-8 and other codecs.
Support for right to left languages.