Organism development refers to the process by which a living organism grows and matures from a single cell into a complex structure. This process involves various stages, including fertilization, cell division, and differentiation, where cells become specialized for specific functions. The development is guided by genetic information encoded in the organism's DNA. During development, organisms undergo significant changes in shape, size, and function. For example, in humans, the development starts with a fertilized egg that divides and forms tissues and organs. Environmental factors and interactions with other organisms can also influence development, leading to variations in growth and form.