Adding abbreviations gives you an autocorrect-like feature. These can be added to your .vimrc file for default settings.
mapping keys can help you automate regular commands. These can also be added to your .vimrc file for default settings
vim is a modal text editor, meaning it supports an array of modes for the user. This in turn necessitates that the user has to specify the mode for each mapping, or to have it encompass all modes (except for insert mode) with the general 'map'.
There is also recursive support, meaning if you map a key to a command, then map another key to the previous key, then the mapping will recursively lead you to the original command. To disable recursive mapping for a particular mapping you would map it with the
and so on.
nmap m o<Esc>
:nmap zz :%s/\s\+$//<ENTER>