Numpy array, what is that?

So I was reading a lot about things in scripts depository. I just learned how to change the background color to white and I am interested to learn more about python in general.

I read a lot and a word 'numpy array" keeps coming up.

What is a “numpy array”?

Get axial slice as numpy array

import SampleData
volumeNode = SampleData.SampleDataLogic().downloadMRHead()
sliceIndex = 12

voxels = slicer.util.arrayFromVolume(volumeNode)  # Get volume as numpy array
slice = voxels[sliceIndex:,:]  # Get one slice of the volume as numpy array

Numpy array is the de facto standard for storing n-dimensional array data in Python. You can process these arrays using functions implemented in numpy and in hundreds of thousands of other Python packages.