Departmentation refers to dividing work into departments based on similarity of functions. There are two main types: functional departmentation, which groups activities by similarity of functions; and divisional departmentation, which creates divisions with their own functional activities. Functional departmentation provides specialization but can lead to delayed decisions, while divisional structures allow faster decisions but challenge coordination. The document discusses various bases for departmentation including products, processes, customers, geography, time, size, and task forces. The choice of departmentation method depends on factors like the work process, specialization needs, technology, and environment.