Deep Learning Textbook by Ian Goodfellow, Yoshua Bengio and Aaron Courville

A good online textbook to start with deep learning, is available here:

https://www.deeplearningbook.org/

Goodfellow, I., Bengio, Y., & Courville, A. (2016). Deep learning. MIT press.

Authors:

Ian Goodfellow - Apple. Previous: Google Brain, OpenAI
Yoshua Bengio - Université de Montréal
Aaron Courville - Université de Montréal

Video introduction to deep learning:

Learn Deep Learning in 6 Weeks (YouTube video by Siraj Raval)