Keratinization is a biological process involving the conversion of epidermal cells into strongly fibrous, water-resistant cells known as keratinocytes, which occur in vertebrates. Synonyms for keratinization include cornification, squamation, and keratinocyte differentiation. Cornification is a term often used in veterinary and veterinary dermatology literature, referring to the process occurring in the outermost layers of most epithelial tissues. Squamation is the process of forming scales in fishes and reptiles, with the keratinization occurring on the scales. Keratinocyte differentiation, as the name suggests, refers to the maturation of keratinocytes from their precursor cells.