Backpropagation Through Time - What is the difference between the backpropagation algorithm and backpropagation through time one?

Recurrent Neural Networks (RNNs) process sequence data, including time series, and one way to apply the normal backpropagation method to these networks is called Backpropagation Through Time (BPTT). All RNN timesteps take in a single input and output prediction. To put it simply, BPTT runs by unfolding each timestep that is supplied.