Beginner's Guide to Compilation in Java Java applications are complied to bytecode then JIT and JVM takes care of code execution. Here you will find some insights about how JIT compiler works. by Join the DZone community and get the full member experience.Join For Free I am guessing that many of you use Java as your primary language in your day-to-day work. Have you ever thought about why HotSpot is even called t or what the Tiered Compilation is and how it relates to Java? I will answer these questions and a few others through the course of this article. I will begin this by explaining a few things about compilation itself and the theory behind it.