matplotlib.pyplot is a collection of command style functions where each pyplot function makes some change to a figure: e.g., creates a figure, creates a plotting area in a figure, plots some lines in a plotting area, decorates the plot with labels, etc. In matplotlib.pyplot various states are preserved across function calls, so that it keeps track of things like the current figure and plotting area, and the plotting functions are directed to the current axes.

Refer https://matplotlib.org/users/pyplot_tutorial.html

NumPy is a library for the Python programming language, adding support for large, multi-dimensional arrays and matrices, along with a large collection of high-level mathematical functions to operate on these arrays.

Refer https://docs.scipy.org/doc/numpy-dev/user/quickstart.html

Pandas offers data structures and operations for manipulating numerical tables and time series. It allows creation and manipulation of dataframes.

Refer http://pandas.pydata.org/pandas-docs/stable/10min.html