What does LangChain do?

What does LangChain do? It turns large-language-model (LLM) tinkering into structured software engineering. The open-source framework supplies interchangeable building blocks—Loaders to ingest data, Embeddings & Vector Stores to search it, Chains to orchestrate prompts, Agents & Tools to let the model act, and Callbacks to log tokens, latency, and cost. With these pieces you can build a Retrieval-Augmented Generation (RAG) chatbot, a code-fixing copilot, or a multi-agent workflow in under 100 lines of Python or TypeScript. Swap GPT-4 for Llama 3, Pinecone for FAISS, or add a reranker with a one-line change, all while tracing every prompt for evaluation. In short, LangChain abstracts away model churn and infrastructure so teams focus on product logic—taking an idea from notebook to production microservice without rewriting core code.