Question

what is the calories

Answer 1

calories:
the energy needed to raise the temperature of 1 kilogram of water through 1 °C, equal to one thousand small calories and often used to measure the energy value of foods.

Answer 2

it is the unit of energy . It's defined by various means but it is defined as the amount of heat required at 1atm to raise the temperature of 1 kilogram of water through 1 °C (originally) .....otherwise it is defined in terms of nutrition also.