Keratinocytes are the primary cells found in the outer layer of the skin, known as the epidermis. They play a crucial role in forming a protective barrier against environmental damage, pathogens, and water loss. These cells produce a protein called keratin, which helps to strengthen the skin and make it resilient. As keratinocytes mature, they move from the deeper layers of the epidermis to the surface, where they eventually die and shed off. This process, known as keratinization, is essential for maintaining healthy skin and ensuring that the outer layer remains effective in its protective functions.