What does the term endothermic signify in a reaction?

Endothermic reactions are characterized by their ability to absorb heat energy from the surroundings. This absorption of heat causes a decrease in the temperature of the surrounding environment. In many cases, endothermic reactions are associated with processes like photosynthesis, where plants absorb sunlight to convert carbon dioxide and water into glucose and oxygen. Because of this heat absorption, endothermic reactions often require a heat source to proceed, distinguishing them from other types of reactions that might release energy instead.

In contrast, reactions that release heat energy are termed exothermic, while spontaneity and gas production do not specifically relate to the heat exchange characteristic of endothermic reactions.