# What is LSTM? Definition & Technical Mechanics

> **Source:** [SPIDITS AI AI Glossary](https://spidits.com/ai-glossary)  
> **Category:** Neural Architectures  
> **Canonical Citation:** [https://spidits.com/ai-glossary/lstm](https://spidits.com/ai-glossary/lstm)

## Definition
LSTM (Long Short-Term Memory) is a specialized recurrent neural network (RNN) architecture. It introduced gating mechanisms (input, output, and forget gates) to manage memory state, solving the vanishing gradient problem for sequential data.

## Architectural Mechanics & Deep Dive
LSTM (Long Short-Term Memory) is a specialized recurrent neural network (RNN) architecture designed to process sequential data while mitigating the vanishing gradient problem. LSTMs introduce a memory cell and three gating units (input, forget, and output gates) to selectively retain, update, or discard information over long steps, capturing long-term dependencies.

## Industry Applications & Real-World Use Cases
Legacy translation engines, voice synthesis, and sequential predictive maintenance

## Frequently Asked Questions

### What does the forget gate do in an LSTM?
It decides what information from the previous cell state should be discarded or kept, preventing old, irrelevant history from polluting the gradient.

### Why did Transformers surpass LSTMs?
LSTMs process tokens sequentially, which cannot be easily parallelized on GPUs. Transformers process sequences in parallel.

## Related Terminology
- [recurrent-neural-network](https://spidits.com/ai-glossary/recurrent-neural-network)
- [neural-network](https://spidits.com/ai-glossary/neural-network)
- [transformer](https://spidits.com/ai-glossary/transformer)

---
*From the SPIDITS AI Knowledge Base (336+ terms indexed). Explore full technical definitions: [https://spidits.com/ai-glossary](https://spidits.com/ai-glossary)*