Like charges repel each other due to the fundamental force known as the electromagnetic force. This force is one of the four fundamental forces of nature and is responsible for interactions between charged particles.

The electromagnetic force between two charged particles, such as two positively charged particles or two negatively charged particles, is governed by Coulomb's Law. Coulomb's Law states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.