Isaac newton and Gottfried Wilhelm Leibniz are credited with inventing calculus independently of each other around the same time. Each used his own notation. Calculus is more commonly associated with Newton than with Leibniz.
Sir Isaac Newton. He and Leibniz both invented the calculus independently.
discovered
Newton Invented it for his theory of gravity.
Issac Newton and Gottfried Leibniz invented the calculus and argued the rest of their lives over who had the priority in this invention.
Gottfried Leibniz.
People use calculus today for the weather for example
Integral calculus was invented in the 17th century with the independent discovery of the fundamental theorem of calculus by Newton and Leibniz.
The biggest impact I think of: Calculus is how people invented the formulas to get the volume and surface area of spheres/cones/pyramids.
Greece
Sir Isaac Newton. He and Leibniz both invented the calculus independently.
Newton and Leibniz simultaneously and independently invented calculus.
Liebniz.
discovered
Calculus was invented or rather can be detailed as back as 1820 B.C. when the Egyptians used it in order to calculate the volume of the pyramidal frustum
Newton Invented it for his theory of gravity.
If you mean "who invented calculus", then Isaac Newton and Gottfried Leibniz both developed it independently.
Calculus was invented to solve physics problems, so the importance of studying calculus is to solve physics problems.