Human development is a continuous and multidimensional process that begins at conception and continues throughout the lifespan. In behavioural sciences, development refers to systematic changes in an individual’s physical structure, psychological processes, behaviour, abilities, and social relationships. Development does not occur in only one area; rather, different domains develop simultaneously and influence one another. The major domains of development are physical development, cognitive development, emotional development, social development, language development, and moral development. Understanding these domains helps explain how individuals grow, learn, behave, and adjust to their environment at different stages of life. Physical development refers to changes in the body, brain, sensory abilities, motor skills, and overall physical health. It includes changes in height, weight, body proportions, muscle development, coordination, puberty, and neurological functioning. During infancy, physical development is particularly rapid. For example, a baby gradually develops the ability to hold its head, sit without support, crawl, stand, and eventually walk. These changes reflect the development of gross motor skills. Fine motor development involves the coordinated use of smaller muscles. For example, a young child first learns to grasp objects with the whole hand and later develops the ability to hold a pencil and write. During adolescence, physical development includes puberty, growth spurts, development of secondary sexual characteristics, and hormonal changes. Physical development continues in adulthood through changes in strength, health, and sensory functioning and later includes ageing-related changes. Cognitive development involves changes in thinking, memory, attention, perception, reasoning, problem-solving, intelligence, and decision-making. It