The document discusses Long Short Term Memory (LSTM) networks, which are a type of recurrent neural network capable of learning long-term dependencies. It explains that unlike standard RNNs, LSTMs use forget, input, and output gates to control the flow of information into and out of the cell state, allowing them to better capture long-range temporal dependencies in sequential data like text, audio, and time-series data. The document provides details on how LSTM gates work and how LSTMs can be used for applications involving sequential data like machine translation and question answering.