This course guides developers through Java’s evolution from version 8 to 21, focusing on modern features that enhance code readability, performance, and efficiency. It starts with Java 8 fundamentals like lambdas, functional interfaces, and the Streams API, enabling a shift from imperative to declarative programming. Learners will set up their development environment and understand why Java 8 was a transformative release. As the course progresses, participants explore features from Java 9 to 21, including the Java Platform Module System (JPMS), local variable type inference (var), text blocks, enhanced switch expressions, records, sealed classes, and pattern matching. Object-oriented programming improvements and functional programming techniques are emphasized to help developers write concise, type-safe code. Practical modules cover parallel streams, the modern HTTP client, and date/time APIs for robust scheduling. The course culminates in a real-world CheckoutService application using sealed classes, a simple web server, and modern Java tooling. By the end, developers will have an up-to-date skill set to confidently build scalable, enterprise-grade Java applications.