Electrochemical discharge machining (ECDM) is distinguished as a novel process that involves thermal heating and chemical dissolution for the micro-machining of "difficult-to-machine" materials like ceramics, quartz. This paper comprehensively reviews the study on gas film, the effect of various input parameters on ECDM performance, such as electrical parameters, electrolyte parameters, and tool electrode parameters, are also likewise discussed. Moreover, a summarized report on thermal modeling, gas film, discrete input parameters, hybridization, and variants in the ECDM process are also provided in a lucid manner. Based on the review, it is concluded that the machining performance of the ECDM process especially in terms of MRR, roughness, tool wear, and thermal cracks are strongly influenced by the input parameters. The formation of the gas film induces variable machining features that can be controlled by altering the machining conditions. Additionally, the paper highlights the future areas that may leads to improve the overall machining performance of the ECDM process.