Abstract
At the heart of Java technology lies the Java Virtual Machine (JVM) - the abstract computer which makes Java's "write once, run anywhere" slogan a valid one. This paper introduces Java's existing JVM features and the way they contribute to its overall portability. It also discusses the future direction of JVM as the characteristics of the overall system infrastructure are evolving rapidly with the emergence of Java Development Kit (JDK), PersonalJava, EmbeddedJava and CardJava.