Chemical etching is very popular inexpensive technique to study dislocations on crystalline faces. The reason for formation of etch pits at the emergence of dislocations and various tests to confirm the formation of dislocation etch pits are discussed as the etch pit formations do not take place at the dislocations only. The morphology of etch pits and composition of etchants are discussed along with various factors affecting dislocation etch pits. The experimental technique is explained along with evaluation of different kinetic and thermodynamic parameters. This technique looks simple, but the selection of etchant composition is seldom simple, which requires certain care to be taken. The main applications of chemical etching are given.