The cell membrane separates the intracellular material (the contents inside the cell) from the extracellular material (the environment outside the cell).

Here's a breakdown:

* Intracellular material: Includes the cytoplasm, organelles, and the cell's genetic material (DNA).

* Extracellular material: Includes the interstitial fluid (the fluid that bathes the cells), other cells, and the extracellular matrix (a network of proteins and carbohydrates that provides structural support and helps regulate cell behavior).

The cell membrane is a selectively permeable barrier, meaning it controls what can enter and exit the cell. This is essential for maintaining the cell's internal environment and ensuring its proper functioning.