On the road.

Qaṣr means shortening prayers when travelling. It’s a mercy from Allah, not a burden — and it’s the recommended way to pray on a journey.

• Dhuhr, ʿAṣr, and ʿIshāʾ are shortened from 4 rakʿahs to 2. Fajr (2) and Maghrib (3) are not shortened.
• Threshold for travel: traditionally a journey of around 80–90 km (about 48 miles) or a day’s travel. Schools differ slightly — follow your madhab.
• You may also combine Dhuhr + ʿAṣr and Maghrib + ʿIshāʾ when travelling, either at the time of the earlier or the later prayer. (Hanafi school does not generally permit combining except at Hajj.)
• Qaṣr begins when you leave your city limits and ends when you return — or, by majority opinion, when you intend to stay 4+ days at a destination.