In this episode, we clarify the distinctions between key cellular terms: protoplast, protoplasm, nucleoplasm, cytoplasm, and cytosol. Protoplast refers to everything inside the cell membrane, excluding the cell wall, while protoplasm, an older term, covers the cell’s contents except for the membrane and wall. Nucleoplasm consists of the materials within the nucleus, while cytoplasm surrounds the nucleus and includes organelles, cytoskeleton, and cytosol. Cytosol, the gel-like fluid of the cell, serves as the site for many metabolic activities. We also explain how terms like “stroma” and “matrix” are used in specific contexts and explore the roles of ectoplasm and endoplasm, two forms of cytosol with unique positions within the cell.