All the diverse groups of organisms are placed in two major groups called the plants and animals from the very ancient times.
Greek philosophers, Aristotle (384- 322 HC) and his disciple Theophrastus underlined the importance of classification of the living organisms.
They classified plants and animals into subgroups on the basis of certain similarities and dissimilarities among them. Carolus Linnaeus (1707-1778), who is known as the father of modern botany or father of taxonomy, divided organisms into two kingdoms such as plantae and animalia on the basis of certain structural and functional characters. The plant cells have a cell wall that exists outer to the plasma membrane. Generally, the plants have ability to synthesize their own organic food.
All the higher plants are, by and large, static and have no ability to move from one place to another. Further the plants are less responsive to external changes in their environment.
Animal kingdom lacks the nonliving component of the cell called the cell wall. They do not synthesize their own food and hence are dependent on the plants for food, directly or indirectly.
The animals, therefore, are heterotrophic. Animals move about freely for various purposes like food, shelter etc. Animals react instantly to stimuli or any changes in the environment. The Characters that separate plants from animals are given in.