What is endocytosis ? How many types of endocytosis are there?

Endocytosis is the process of active cellular intake of materials. It involves invagination of a small region of plasma membrane, forming an intracellular membrane bound vesicles. It is of two types :
(a)Pinocytosis is a process of intake of droplets of extracellular fluid.
(b)Phagocytosis is a process of intake of solid particles.