Write a short note on Keys.

Explanation

A key in an analytical scheme for identification of plants and animals based on the similarities and differences. The keys are based on the contrasting characters, generally in a pair called couplet.
Each couplet actually represents the choice made between tow opposite options,leading to the acceptance of one. Each statement in the key is called a lead keys are of two types.
(1) Indented keys : Which provides a sequence of choices between two or more state-ments of character of species .
(2) Bracjeted keys : where pairs of contaradicting characters are used for identification, the number on the right of the statement indicate the recent choice of paired contrasting statements .