The Sun JRE consists of a redistributable executable, some DLLs, and some class files. It is one component of the Sun Java SDK, but a number of other Windows applications include or depend on a JRE.
For simplicity, we'll consider the Microsoft JVM that came with Windows ME to be a Sun JRE, as well.
Native Alternatives:
Sun provides its JRE for Solaris and Linux. See java.sun.com for the free download.
Kaffe is a clean room implementation of the Java virtual machine, plus the
associated class libraries needed to provide a Java runtime environment.
