One of the most common temperature changes in a real world is our body temperature. When we have some infections or viral infections, our cells reacts to the foreign substance and fighting it in order to maintain the homeostasis. As a result, the immune system will signal the brain to increase the body temperature thus causing us to be warmer.
Antipyretics on the other hand are medicine used to lower down the temperature of the body. Antipyretics will signal the hypothalamus to control the increased in temperature thus making the fever goes down.
When you add salt to ice it lowers the temperature. This is how ice cream is made at home. Your freezer temperature is at least 10 degrees F and that is about the temperature of the ice and salt. The salt breaks the bonds between the ice molecules which uses energy to do this and the temperature lowers. This is called an endothermic reaction. Endo- means in referring to energy being taken as opposed to released as in exothermic reactions. 0 degrees Centigrade was the coldest a scientist got the temperate of an ice and salt mixture to go and was used as a benchmark for the Centigrade scale. One hundred was given to the value that water boils at.