Series: Definitions

This lecture introduces the concept of infinite sums, also known as series, as a way to define the sum of an infinite sequence of real numbers. The instructor explains the terminology related to series convergence and divergence, emphasizing the importance of absolute convergence. Various examples are provided to illustrate these concepts, including the calculation of the sum of convergent series. The lecture concludes with a discussion on the properties of absolutely convergent series and the criteria for convergence, such as the Cauchy criterion.