A neural network with loops for handling data in order.
An RNN is like a kid watching a show one episode at a time. Before the next episode, it remembers who stole the lunch money.
You meet it in speech, text, and numbers over time. For long memory jobs, newer models often take over.
Sequence Modeling
RNNs were one of the main early models for sequence data.
BPTT
BPTT unrolls an RNN through time, then uses backpropagation.
LSTM
LSTM adds gates to an RNN, so it forgets less over long spans.
Transformer
Transformers later replaced RNNs in many sequence tasks.