LangChain provides interfaces and integrations for two types of models:
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
- [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.
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.
The APIs they wrap take a string prompt as input and output a string completion. OpenAI's GPT-3 is implemented as an LLM.