Newton introduced the basic notion of inverse function
called the anti derivative (indefinite integral) or the inverse method of tangents During 1684-86, Leibnitz published an article in the Acta Eruditorum
which he called Calculas summatorius, since it was connected with the summation
of a number of infinitely small areas, whose sum, he indicated by the symbol ‘∫’ In 1696, he followed a suggestion made by J Bernoulli and changed this article to
Calculus integrali