Final answer:
The movement of molecules from an area of higher concentration to an area of lower concentration is known as diffusion, a type of passive transport.
Step-by-step explanation:
The process in which molecules, ions, or particles move from an area of higher concentration to an area of lower concentration is known as diffusion. This is a form of passive transport where substances move along the concentration gradient without the requirement of energy.
Osmosis is a special type of diffusion, specifically referring to the movement of water across a semipermeable membrane due to a difference in concentration. It is not to be confused with active transport, which is the movement of molecules against their concentration gradient and requires energy, often in the form of ATP.