I am reading the "Lectures on the Geometry of Manifolds" by Liviu I. Nicolaescu.
I come across the term smooth map for many times, but I don't really get the meaning of it.
I googled online, but they would use "chart" to define it, e.g. "Smooth maps between smooth manifolds may be defined by means of charts, since the idea of smoothness of function is independent of the particular chart used ." (wiki), and they really draw a chart (http://www.math.toronto.edu/mat1300/smoothmaps.4.pdf).
But is there any more easy way to understand it? Or if I should read something relative to it in order to understand it ?