LangChain provides interfaces and integrations for two types of models:
- [LLMs](/docs/modules/model_io/models/llms/): Models that take a text string as input and return a text string
- [Chat models](/docs/modules/model_io/models/chat/): Models that are backed by a language model but take a list of Chat Messages as input and return a Chat Message
- [LLMs](/docs/modules/model_io/models/llms/): Models that take a text string as input and return a text string
## LLMs vs chat models
## LLMs vs Chat models
LLMs and chat models are subtly but importantly different. LLMs in LangChain refer to pure text completion models.
The APIs they wrap take a string prompt as input and output a string completion. OpenAI's GPT-3 is implemented as an LLM.