# Model Archetypes

- [Decoder-only (GPT)](./decoder-gpt.md) — Causal, autoregressive. The dominant architecture for generative LLMs.
- [Encoder-Decoder (T5)](./enc-dec-t5.md) — Encoder reads input, decoder generates output. Natural fit for seq-to-seq.
- [Encoder-only (BERT)](./encoder-bert.md) — Bidirectional, trained with masked language modeling. Best for understanding, not generation.
