Explore the creation of five distinct Langchain applications for summarization and question-answering using Chromadb as an OpenAI embeddings vector store. Learn to leverage the GPT-3 API for document summarization and context-based question answering. Discover techniques for token counting and custom prompt building in Langchain. Gain hands-on experience with various chain types, including "stuff," "map reduce," "refine," and "map rerank." This 20-minute tutorial covers installation from scratch, code reviews for summary generation, and implementations of different chain types, providing a comprehensive overview of Langchain's capabilities in natural language processing tasks.