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LangChain Fundamentals

Introduction to LangChain

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What is LangChain?

LangChain: Building Blocks for LLM Applications

LangChain is a framework for developing applications powered by language models. It provides:

  • Composable Components: Modular abstractions for working with LLMs
  • Off-the-shelf Chains: Pre-built assemblies for common tasks
  • LCEL: LangChain Expression Language for building custom chains

Why Use LangChain?

Without LangChainWith LangChain
Manual API calls to each providerUnified interface for all LLMs
Custom prompt managementPromptTemplates with variables
DIY memory implementationBuilt-in conversation memory
Manual RAG pipelineVector stores + retrievers

Core Philosophy

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This composability is the heart of LangChain.