In response to Siraj Raval's "How to Make a Neural Network - Intro to Deep Learning #2".
This is a neural network with 3 layers (2 hidden), made using just numpy. It's an adapted version of Siraj's code which had just one layer. The activation function used in this network is the sigmoid function.
Here is a pictorial illustration:
A screenshot of the code where the weights are updated after running the backpropagation adjustments.