Introduction to Deep Learning
Start with this overview blog post and a very recent addition.
Now it’s time to look at some specific techniques. Dig as deep as you like! These websites provide plenty of background information.
Deepvis (code and paper are linked, optional further reading on fooling neural nets)
LSTMVis (code and paper are linked)
Heatmapping - especially Methods for Interpreting and Understanding Deep Neural Networks (2017), Montavon et al.
Be critical about the introspection methods you use! Sanity Checks for Saliency Maps (2018), Adebajo et al.