langchain/docs/docs/modules/model_io/index.mdx

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  description: Interface with language models
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# Model I/O

The core element of any language model application is...the model. LangChain gives you the building blocks to interface with any language model.

![Flowchart illustrating the Model I/O process with steps Format, Predict, and Parse, showing the transformation from input variables to structured output.](/img/model_io.jpg "Model Input/Output Process Diagram")

## [Conceptual Guide](/docs/modules/model_io/concepts)

A conceptual explanation of messages, prompts, LLMs vs ChatModels, and output parsers. You should read this before getting started.

## [Quickstart](/docs/modules/model_io/quick_start)

Covers the basics of getting started working with different types of models. You should walk through [this section] if you want to get an overview of the functionality.

## [Prompts](/docs/modules/model_io/prompts/)

[This section](/docs/modules/model_io/prompts/) deep dives into the different types of prompt templates and how to use them.

## [LLMs](/docs/modules/model_io/llms/)

[This section](/docs/modules/model_io/llms/) covers functionality related to the LLM class. This is a type of model that takes a text string as input and returns a text string.

## [ChatModels](/docs/modules/model_io/chat/)

[This section](/docs/modules/model_io/chat/) covers functionality related to the ChatModel class. This is a type of model that takes a list of messages as input and returns a message.

## [Output Parsers](/docs/modules/model_io/output_parsers/)

Output parsers are responsible for transforming the output of LLMs and ChatModels into more structured data. [This section](/docs/modules/model_io/output_parsers/) covers the different types of output parsers.