Cytoplasm is the substance that fills the inside of a cell and houses most of its internal structures, except for the cell nucleus and mitochondria. It consists of cytosol, the liquid component of cytoplasm, organelles, or structures inside the cell with a specific function, and inclusions, which are nonliving components which are found in the cell, such as lipids. 

Most cellular activities and processes, such as cell division, occur within the cytoplasm. The movement of calcium ions in and out of cytoplasm is thought to be a signaling activity for metabolic processes.