All naturally occurring processes proceed spontaneously in a direction which leads to an increase in the entropy of the universe.

Entropy is a measure of disorder or randomness. This principle is a fundamental concept in thermodynamics, often referred to as the Second Law of Thermodynamics.

In simpler terms:

• Spontaneous Process: A process that occurs without external intervention.
• Entropy: A measure of the disorder or randomness of a system.

So, natural processes tend to move towards a state of greater disorder or randomness. For instance, heat flows from a hot object to a cold object, gases expand to fill a container, and ice melts at room temperature. All these processes increase the overall disorder of the universe.