JRuby allows Ruby code to run on the Java Virtual Machine. It provides the ability to reuse existing Java libraries and deploy Ruby applications in scalable and enterprise-ready environments. While Java may have a reputation for being slow, JRuby performance is on par with CRuby for most web applications due to JIT compilation optimizations in the JVM. Calling between Ruby and Java code is seamless, allowing Ruby code to leverage Java libraries and Java code to leverage Ruby code. JRuby applications can be packaged and deployed like standard Java applications.