LangChain is an open-source orchestration framework that simplifies building applications with large language models (LLMs). It provides tools and components to connect LLMs with various data sources, enabling the creation of complex, multi-step workflows. Available as libraries in Python and JavaScript, LangChain helps developers enhance LLM capabilities beyond text generation by linking them to external data and computation. Key features include prompt orchestration, conversational memory management, modular architecture for flexible component swapping, and support for Retrieval Augmented Generation (RAG) workflows that reduce hallucination and improve response accuracy.