To understand how the modern Calculus was formalized, we have to go back in time from the late 16th to early 17th century. From there, there were two mathematicians, Newton and Leibiniz, who came out with two different concepts, but arrived at the same Calculus that the students are learning in the mathematical curriculum now. How did this happen? This book illustrates the above in a comprehensive manner, where it writes about the derivation of Calculus from both mathematicians, and some results from them and their disciples via Calculus.