There are many types of cells in the human body, which can be categorized into hepatocytes, cardiomyocytes, renal cells, small intestinal epithelial cells, and so on, according to the organs. According to the morphology of the cells, they can be divided into flat cells, columnar cells, astrocytes and so on. According to the composition of intracellular organelles, they can be divided into nucleated cells and non-nucleated cells. The skin is the largest organ in the human body and, therefore, contains the largest and most comprehensive variety of cells. The skin contains the stratum corneum and therefore has keratinocytes, which are the non-nucleated cells. Below that there are granulosa cells and flattened epidermal cells, also called keratin-forming cells. There are also blood vessels in the skin, hence there are epithelial cells, and red blood cells, which are non-nucleated. There are also phagocytes, Langerhans cells, lymphocytes, and astrocytes for neurotransmission in the skin’s immune system, to name a few.