A sugar thermometer is a thermometer designed for measuring the high temperatures of boiling sugar syrups in confectionery and jam making. It typically reads from around 40°C up to 200°C, with the critical sugar stages marked on its scale: thread, soft ball, firm ball, hard ball, soft crack, hard crack, and caramel. Knowing the exact stage is essential because a few degrees separate a chewy caramel from a brittle toffee. The thermometer clips to the side of the pan so the bulb sits in the syrup without touching the base, which would give a falsely high reading. Digital probe thermometers now do the same job faster, but the traditional glass sugar thermometer remains a fixture in professional pastry kitchens.