A cartographer is a person who makes maps — not the activity itself (that is cartography), though the two words sit so close that learners mix them constantly. A cartographer does more than colour in countries. They decide what to show and what to hide, how to flatten a round world onto a flat page, and how to mark roads, hills, and borders so you can trust the picture. Today many work on computers, making the maps inside phones and sat-nav, not only paper atlases. The word is a bit formal; in easy talk people often just say map-maker.