Thermo Gravimetric Analysis (TGA) is a pivotal technique in thermal analysis, measuring the mass of a substance as a function of temperature. It plays a crucial role in elucidating materials undergoing mass changes during thermal events such as decomposition, oxidation, and reduction. This chapter explores TGA principles, types, and instrumentation, including microbalances, autosamplers, thermocouples, furnaces, temperature programmers, and recording systems. Understanding the working of TGA involves considerations like sample preparation, heating rates, and purge gas selection. Calibration procedures, such as blank tests and temperature/mass calibration, ensure accurate results. Factors influencing TGA curves, including instrumental factors, sample characteristics, and particle size, are discussed, providing insights into the advantages and disadvantages of the technique. TGA finds diverse applications in pharmaceuticals, biomedicine, chemistry, forensic science, and food science, offering valuable information for research and quality control. The chapter concludes with a comprehensive exploration of TGA curve analysis, elucidating the complexities and subtleties of this powerful analytical method.