vim macros are a quick way to perform repetitive tasks quickly. To start recording a macro, use q followed by what letter you want to save the macro on, do the work you want to repeat, and then press q again to stop recording.
For example (<enter> is a literal enter in this case):
qa80lBhr<enter>q
This would record a macro on the a key, then move 80 characters to the right, move to the
beginning of the current word, move one letter to the left, and replace that with a \n, and stop
recording. I use this to quickly wrap lines at 80 characters.
To use the macro, use the @ key, then the key where you recorded the macro. For the above, @a
will run the macro.
Advanced mode, would be 7@a to execute the macro 7 times. The advantage to using 7@a is that
undo will undo all 7 instances.