title: What is the best way to add a custom key mapping in vim/vi? (Does there exist a unbound keyspace for customization?)
body: <p>I know you can add custom keymappings to vim with <code>imap</code> in the <code>.vimrc</code> file. My question is, if one is to create additional custom operators, motions, commands and map them to keys, what is the best way to add them in so they don't conflict with existing bindings?</p>
  
  <p>An analogy, in emacs, a lot of custom key commands are added via the C-c  sequence. To be more technical, are there unbound keys in vim that allow for user customization? In other words, is there a free keyspace available to users?</p>