Vitamins are essential nutrients necessary for the body's growth and function, introduced by biochemist Casimir Funk, with the term originating from 'vital' and 'amines'. They are categorized into fat-soluble and water-soluble vitamins, each with distinct sources, functions, and deficiency disorders. Key vitamins include A, B-complex, C, D, E, and K, sourced from various animal and plant foods, with deficiencies leading to health issues such as anemia and scurvy.