Recurrent Neural Networks
Definition
Artificial neural networks are parameterized models built from layers of connected computational units. Training adjusts the parameters to reduce an objective function.
What is a recurrent neural network?
A recurrent neural network, or RNN, processes a sequence while carrying a hidden state from one step to the next. The state acts as a numerical summary of previous inputs.
Why recurrence was useful
Language, speech and time series have order. RNNs provided a natural way to process one element at a time while allowing earlier information to influence later outputs. They were widely used before transformers became dominant in large-scale language modeling.
The long-range problem
Basic RNNs can suffer from vanishing or exploding gradients, making long-distance dependencies difficult to learn. LSTM and GRU architectures added gates that improved long-term information flow. Transformers later removed recurrence entirely for many sequence tasks.
Related terms, defined
Reference guide and primary sources
Wikipedia is used here as a terminology and history reference guide. Current model versions, institutional statistics and product-specific claims are also linked to first-party or institutional sources because those details can change faster than encyclopedia articles.