This book introduces you to web development with Rust and Leptos. To begin with, you install a solid Rust toolchain and set up Leptos in VS Code, and then you see your first "Hello World" interface rendered via WebAssembly right away. So, first you'll design a microservice-inspired book-selling sample app, called LibroCommerce, into inventory, orders, and user accounts. Then, you'll connect each piece with Axum handlers, SQLx queries, and shared Serde models. By the time you get to Chapter 3, you'll have built a nonblocking, Tokio-driven server that handles dynamic routes, powers Leptos SSR pages, and secures endpoints with JWT and OAuth2. Then, you add real-time features: WebSockets send stock updates and order-status events to reactive Leptos signals, keeping the UI and backend in sync. As you go, you'll be writing end-to-end Playwright tests and setting up GitHub Actions so that every commit runs Rust tests, Playwright scenarios, Docker builds, and Kubernetes rollouts automatically. You'll learn how to connect to PostgreSQL with an async pool, model Books, Users, and Orders with Serde-annotated Rust structs, and implement CRUD, password hashing with Argon2, encrypted backups, and session stores in Redis. Performance tuning shows you how to optimize Tokio threads, tune SQLx pools, stream large result sets, debounce client inputs, and apply backpressure. At last, you put each microservice and frontend into Docker containers, deploy them with Kubernetes, and then use serverless. Key Learnings Start using Rust and Leptos with VS Code to develop web applications using WebAssembly. Architect microservices with inventory, orders, and user modules for modular, scalable applications. Make servers that respond to user activity and are not blocked by other users. Use Tokio and Axum with dynamic routing and concurrency. Employ business logic with SQLX, transactions, and external API integration for real-world workflows. Protect your devices with JWT, OAuth2, Argon2 password hashing, HttpOnly cookies, and TLS encryption. Handle database state asynchronously, define Serde data models, and perform efficient CRUD operations. Utilize WebSockets, Leptos signals, and broadcast channels to enable real-time updates. Perform end-to-end testing with Playwright, integration tests, and automated CI pipelines for reliability.