You have probably seen something like this in other editors. Macros (or "complex repetitions" as Vim's help puts it) is a way to repeat complex commands sequences. In order to get the most out of this feature, you need to master movement and insertion commands.
The work cycle is the following: start recording, execute commands, stop recording. Then, you are ready to execute the whole sequence of commands you have recorded. Let us see this in more detail. To start recording, we use the "q" command followed by a register name in which the sequence of commands will be stored.
At that ...