A sensitive period is a time that is best for certain capacities to develop because the individual is especially responsive to environmental influences. However, its boundaries are less well defined than those of a critical period. Research indicates the existence of critical periods or sensitive periods in the various areas of development. The concept of sensitive period is more applicable to language development and social and emotional development. Earlier, it was thought that the early years were a critical period for language development i.e the child was biologically ready at this time to acquire language skills. It was essential to give language exposure to a child if language was to be developed properly.