Developmental stage refers to a distinct phase within a larger sequence of development ; a period characterized by a particular set of abilities, motives, behaviors, or emotions that occur together and form a coherent pattern; period of life dominated by a particular quality of thinking or a particular mode of social relationships.
The notion of stages suggests qualitative changes in competence at each phase of development. Different theories describe a sequence of childhood learning that requires progressively more complex skills and cognitive functions. Each level of learning is typically seen as a stage of development that must be completed before the next stage can be approached. For psychoanalytic thought, stages follow biological functions; for ego psychology, stages follow psychosocial influences; for object relations, stages follow the increasingly sophisticated interactions between the child and caretaker.