Chip time is the time it takes a runner to complete the course, measured from when they personally cross the start line to when they cross the finish line. It's tracked by a timing chip built into the bib or attached to the shoe.
It's your individual elapsed time, counted from the moment you cross the start line to the moment you cross the finish. It's tracked automatically by a chip on your bib or shoe.
Gun time starts counting the instant the starting gun fires, no matter where you're standing. Chip time only starts when you personally cross the start mat, which matters a lot in crowded races.
Most races use chip time as the official personal result, especially in large events with staggered or wave starts. Check the specific event's rules to be sure.
Most organized road races do, but small local or community runs may rely only on gun time. Larger, registration-based events almost always chip-time results.
Because it excludes the minutes you spent walking to the start line before crossing the timing mat. This gap is bigger the further back you start in a large field.