Osmosis is a process by which water molecules move from an area of high concentration to an area of low concentration through a selectively permeable membrane. The term osmosis was first coined by a French physician and biologist, René Joachim Henri Dutrochet, in 1826.
In order for osmosis to occur, there must be a concentration gradient of solute particles (such as salt or sugar) between the two sides of the membrane. The membrane is selectively permeable, which means that it allows certain substances to pass through while others are blocked. In the case of osmosis, the membrane only allows water molecules to pass through, while the solute particles are too large to pass through.
During osmosis, water molecules move from the side of the membrane with a higher concentration of water (lower concentration of solute particles) to the side with a lower concentration of water (higher concentration of solute particles). This movement continues until the concentration of water on both sides of the membrane is equal, or until the pressure on one side of the membrane becomes too great to allow further movement of water molecules.
The direction and rate of osmosis are determined by several factors, including the concentration gradient of solute particles, the permeability of the membrane, the temperature, and the pressure difference across the membrane. Osmosis plays a critical role in many biological processes, such as the movement of water and nutrients into and out of cells. It also has many practical applications, such as in water treatment and food preservation.