The hash is a run or walk with trail set by one or two volunteers, known as the Hares. The Hare(s) lay a 4-10 km trail with biodegradable flour, paper, chalk or sawdust depending on the environment and weather. Trails may pass through any sort of terrain and hashers may run through back alleyways, residential areas, city streets, shopping malls, forests, swamps , or messy areas (known as “shiggy”) and may climb fences, ford streams, explore storm drains or scale cliffs in their pursuit of the Hare.Special marks may be used to indicate a false trail, a backtrack, a shortcut, or a turn. The most commonly-used mark is a Check, indicating that hashers will have to search in any direction to find the continuation of the trail. Trails may contain a Piss-Stop, where the pack stops to consume beer, water, or snacks, allowing any stragglers to catch up to the group.                                  

Hashers often carry horns or whistles to communicate with each other, in addition to verbal communication. Every kennel employs its own set of marks and the names for these marks may vary widely. Additionally, the Hares for that particular run may give some trail-specific advice, such as rare markings or particular obstacles.                  

There are two types of trails. Live Trails (or Live Hares) are laid by Hares who are given a head start, while Dead Trails are pre-laid hours or days before the Hash begins. Live trails are closer to the original "Hare and Hound" tradition, with the intent of the pack being to catch the Hare rather than making it to the end, and are more common in the United States, while the rest of the world tends toward dead trails.    

A trail may be "A to A," where the trail returns to the start, or "A to B," where the beginning and end of the trail are widely separated.