TOPIC: Localise field names

Another (hopefully quick) question - how do I go about localising the field names? That is, changing Zip Code to Post Code.

I've searched for the text strings within the component folder without success, and checked on the forum here for anything with 'localize' or 'localise' in it unsuccessfully.

This IS answered many times in the forum, but just not called "localise" by anyone before. You can make changes in the language files, as all text is pulled from there, like other components do.

FRONTEND:
/language/en-GB/en-GB.com_dtregister.ini

BACKEND ADMIN:
/administrator/language/en-GB/en-GB.com_dtregister.ini