The term "cell surface" refers to the outermost layer or membrane that surrounds and encloses a cell. It is composed mainly of proteins, lipids, and carbohydrates, which together form a barrier between the cell's interior and its external environment. The cell surface plays several important roles in the functioning of cells, including protection, communication, transportation, and sensory functions. It also serves as a site for various biological processes such as cell division, adhesion, and immune response. In summary, the "cell surface" is an essential component that defines the boundaries and characteristics of a living cell.