The present work reports the thermally stimulated luminescence displayed by sodium with different percentages of indium as impurity the doped NaCl: In crystal after exposure to UV light is studied. The thermal glow curves exhibited by NaCl: In shows interesting results. The dependence of dopant concentration on TL in NaCl: In crystal is investigated. The interaction of ionizing radiations with matter leads to various effects, some of which leave memory in the target material. This memory effect can be seen as the after effects of the irradiation. This paper describes the sequence of the physical events beginning with the incidence of an ionizing particle. Leading to trail of atomic and electronic displacements which stabiles in the form of so called defect centers. The kinetics of the thermoluminescence process has been explained phenomenological. The TL phenomenon has found many particle applications. The most outstanding of these are in dosimetry and in archaeology. The paper deals mainly with the physical processes involved in the TL emission and allude briefly to its involvement in applied areas.