Here's a breakdown:

* Endothermic: The prefix "endo" means "within" or "inside." In this context, it refers to the system absorbing heat from its surroundings.

* Exothermic: The opposite of endothermic, meaning heat is released from the system to the surroundings.

Think of it like this:

* Endothermic reactions: Feel cold to the touch because they are taking heat away from you.

* Exothermic reactions: Feel warm to the touch because they are releasing heat towards you.