In order to increase the coefficient of performance of heat exchangers under frosting conditions such as in air conditioners, showcases, and unit coolers, it is necessary to elucidate the frost deposition mechanism. The previous studies about frost deposition were summarized in this study. The previous studies about observation of frost deposition, properties of the frost layer, simulation methods of the frost layer, frost detection, frost studies concerning heat exchangers and heat pumps, and defrost control methods were explained. There are many conditions that have not been measured yet, though the mechanism of frost deposition and properties of the frost layer have been elucidated from the previous studies. The study of frost deposition has been invigorated in Japan recently. The understanding of frosting phenomenon is expected to be deepened in the near future.