* Osmosis is the movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration.

* Isotonic means that the concentration of solutes (dissolved substances) is the same inside and outside the cell.

In an isotonic solution:

* There's no net movement of water into or out of the cell.

* The water potential inside and outside the cell is equal.

* The cell maintains its normal shape and volume.

Think of it like this:

Imagine a cell as a balloon filled with water. If the balloon is placed in a solution with the same water concentration as inside the balloon, the water will move equally in both directions, keeping the balloon at its original size.