What is meant by exothermic and endothermic reactions? Give examples.

Exothermic reaction:
Chemical reactions that release energy in the form of heat, light, or sound are called exothermic reactions.
Example: Mixture of sodium and chlorine to yield table salt

Endothermic reaction:
Reactions that absorb energy or require energy in order to proceed are called endothermic reactions.
For example: In the process of photosynthesis, plants use the energy from the sun to convert carbon dioxide and water to glucose and oxygen.