Because these are what you'll be [using 80%+ of the time](https://en.wikipedia.org/wiki/Pareto_principle).

|   Command   |                       Effect                       |
|-------------|----------------------------------------------------|
| `do`        | **Get** changes from other window                  |
| `dp`        | **Put** changes to other window                    |
| `]c`        | **Next** Change                                    |
| `[c`        | **Previous** Change                                |
| `:diffthis` | Type in each split window to diff existing buffers |
| `:diffoff`  | Type to turn off diff mode                         |

Use <kbd>Ctrl</kbd>+<kbd>w</kbd>, <kbd>Ctrl</kbd>+<kbd>w</kbd> to switch between windows. [Via](https://amjith.blogspot.com/2008/08/quick-and-dirty-vimdiff-tutorial.html).