You can do combat and exploration in theater of the mind without ever using any minis or maps or tokens. You don’t need anything but dice, pen, paper and the rules to play. And maybe a few people.

Many people find it helps to at least visualize the scenario in some situation. Combat is one of the most obvious ones. You can draw on a piece of paper, use dice, random items or whatever else you like to do that. Some people enjoy using miniatures or building terrain set pieces because it’s fun.