Macros are, in a way, similar to aliases. They allow you to send commands to the MUD in an easier way. Aliases allow you to associate commands with shortcuts (typing a three-letter command to send a much more complex command, for example). Macros allow you to associate a command with a keypress. You could associate, for example, F5 with the command drink from fountain, and then you would only need to press F5 to send that command to the MUD.

The commands need not be complex or big: you could associate the arrow keys with macros that send movement commands, and you would be able to move around the MUD using the arrow keys.

Macros consist of a key and an action. The action represents what is sent to the MUD when the macro is run. It can be a single command to send, several commands separated by %;, or something to be executed by Perl, if it starts with /.