Development

Development is the process of change over time as a result of the interaction between environmental and genetic forces. It involves progressive, cumulative changes in structure, function, behavior, or organization. For example, development can refer to change in physical size or shape, mental function, perceptual capacity, or behavior.

Development involves changes that persist over time, rather that those that are temporary or situation-specific. It commonly refers to progressive change toward more complex levels of functioning. For humans, the term often refers to children's growing physical and mental capacities that allow them to participate in their social, intellectual, and cultural worlds. However, the term "development" is properly applied across the entire lifespan and can also refer to changes that are regressive rather than progressive. For example, the reduction in visual acuity that results from aging of the structures of the eye can also be considered a developmental change.

Development can occur gradually and incrementally (quantitative change) or involve stagelike transitions (qualitative change). The term itself is neutral in reference to whether the root cause is environmental or genetic, although different theories of development ascribe different roles to these interacting forces.