After reading the tutorial I was not sure why it was called backpropagation. Thanks for the Colah's blog link. I think the two links together explains the thing

After reading the tutorial I was not sure why it was called backpropagation. Thanks for the Colah's blog link. I think the two links together explains the things beautifully. Backpropagation seems just like an optimization for the gradient descent calculation as per Colah's blog.