It is important that food be cooled as quickly as possible to avoid contamination from harmful bacteria and other microbes. The ‘danger zone’, as it is known, is between 10°C and 65°C.
While the obvious solution is to pop the hot food into the fridge, this is really asking for trouble! This causes the food [especially liquids] to cool quickly on the outside while the centre remains locked in the ‘danger zone’ and additionally, other food in the fridge such as eggs may absorb the unwanted flavours from the hot food. The negative results may not always be obvious or disastrous, especially in strongly flavoured dishes such as curries.