Method of fluxions is a mathematical term introduced by Sir Isaac Newton. It refers to the mathematical technique of calculating derivatives through a process of continuous motion. Since the Newtonian era, many other synonyms or related terms have been used interchangeably, depending on geographical location and teaching style. Some of the common synonyms for the method of fluxions include the calculus, infinitesimal calculus, differential calculus, and integral calculus. Other related terms include differential equations, differential geometry, and partial differential equations. While each of these terms differs in details, they all encompass the same basic concepts and techniques used in the study of calculus, making it one of the most important subjects in modern mathematics and science.