The plasma membrane, also called the cell membrane refers to a double layer of the proteins and lipids, which envelopes a cell and distinguishes the cytoplasm from its surrounding environment. It is selectively permeable, which signifies that it only allows some of the molecules to move in and move out.
All the cells possess a cell membrane, and it performs certain set of functions like determination of chemical messages, active transportation, and protection. All these set of activities plays an essential role in the survival of the cell.