Milk is a natural secretion of the mammary gland of healthy lactating animals, characterized by fat dispersed as an emulsion, proteins and certain minerals present in colloidal form, and lactose along with soluble minerals and proteins existing in true solution. The physicochemical properties of milk are fundamental in determining its nutritional quality, stability during storage, and behavior during processing. The first secretion following parturition, known as colostrum, differs markedly from normal milk in composition and is particularly enriched with immunoglobulins that provide passive immunity to the newborn during the early postnatal period when the immune system is not fully developed. Milk composition varies widely among species, reflecting the specific nutritional needs of their offspring. On average, milk contains about 87% water, 4.9% lactose, 3.5% protein, 3.9% fat, and approximately 0.7% minerals along with vitamins and other minor constituents. It comprises a complex array of nearly 200 proteins exhibiting diverse structural and physicochemical properties. In addition to its basic nutritional role, milk serves as an important source of bioactive peptides that confer multiple health benefits, including antihypertensive, antidiabetic, antioxidant, and antimicrobial activities.