Developing applications with Large Language Models presents a common set of challenges. While a model can generate text, a complete application often needs to connect to other data sources, manage conversational history, and sequence multiple operations. Writing the integration logic for these tasks can be repetitive and complex.

LangChain provides a standard interface and a collection of components to address these requirements. It is a framework for assembling applications from modular pieces, simplifying the development of data-aware and agentic systems. This chapter introduces its main architectural elements: Models, Prompts, Chains, Indexes, Memory, and Agents. Understanding how these parts function is essential for using the framework effectively.

In the following sections, you will configure your development environment by installing the necessary libraries and setting up API credentials. To conclude the chapter, you will apply these initial concepts to build and run a basic application that sends a query to an LLM and receives a response, providing a practical foundation for the topics that follow.