Persistent luminescent materials are an innovative category of substances that exhibit afterglow properties, i.e., light emission that occurs after the source of excitation has been removed. Such types of materials can be activated by various forms of energy, such as UV or visible light, electron beams, plasma beams, X-rays, and γ-rays. A longer emission lifetime without an external energy source offers numerous potential applications, not only in optoelectronic devices but also in fields such as bioimaging, phototherapy, data storage, and security technologies. Most of the persistent luminescent materials exhibit excellent thermoluminescence properties. In thermoluminescence (TL), it gives the release of light when a pre-irradiated semiconductor or insulator is heated. The phenomenon has found wide applications in dating, dosimetry, and defect studies of solid-state materials. The essential condition to show thermoluminescence properties is the presence of traps and recombination centers, commonly called defect centers. These centers may be created either by the incorporation of suitable impurities or by heating up to a high temperature and then subsequently quenching. Sometimes ionizing radiations like X-rays or γ-rays are also used to create the point defects in the materials. The present chapter highlights the mechanism of the persistent luminescence and thermoluminescence phenomena, along with applications in emerging areas. The spectroscopy of deep and shallow traps formed in the phosphor materials based on kinetic analysis of thermoluminescence glow curve structure is also a part of this chapter. For kinetic analysis, the various available methods are summarized, which ultimately yield a number of trapping parameters, including order of kinetics, activation energy, trapped charge carrier density, and frequency factor.