what is the main function of the cell membrane?

The main function of the cell membrane is to protect the cell by acting as a selective barrier that separates the interior of the cell from the external environment. It regulates the movement of substances in and out of the cell, allowing essential nutrients to enter, waste products and toxic substances to exit, and maintaining a stable internal environment. Additionally, the cell membrane supports the cell's structure, facilitates cell communication, and plays a role in tissue formation by connecting with other cells and the extracellular matrix.