The cell is the most basic functional, structural and biological unit of all living organisms; it is the smallest unit of life and the foundational block from which other systems are built. In multi cellular organisms, cells that perform similar functions usually come together to form tissues. Similar tissues then come together to form organs. Organs refers to group of tissues that have specific functions. Related organs finally come together to form organ systems. Organ systems refers to group of organs that work together to carry out complex functions. Thus, in multi cellular organisms, the organization of cells include: cells, tissues, organs and organ system.
