Protoplasm is the substance inside the membrane of a living cell. At the simplest level, it is divisible into cytoplasm and nucleoplasm. It is also sometimes termed bioplasm (Beale; meaning the essential "substance" of living matter within a cell) and distinct from non-living cell components lumped under ergastic substances. Ergastic substances can, but need not, occur in the protoplasm. In many plant cells, most of the volume of the cell is occupied not by protoplasm, but by a large water-filled vacuole enclosed by a membrane, the tonoplast.

The idea that protoplasm is divisible into a ground substance called cytoplasm and a structural body called the nucleus reflects the more primitive knowledge of cell structure that preceded the development of powerful microscopes (see Electron microscope). It was once widely held that life could exist in essentially a "soup" of organic and inorganic substances, mysteriously directed by the nucleus and controlled by the cell membrane. Today, it is known that the cytoplasm is structurally very complex, and that protoplasm is living due to the complexity of the cytoplasmic organelles and their careful separation and orchestration of multiple chemical processes.

Protoplasm is basically the cell contents inside the cell membrane/wall.... i.e the vacuole, nucleus, cytoplasm, chloroplasts etc...