All java virtual machines (JVM) have a system properties class which contains information that varies across different platforms. It includes, for example, the Java version number, Java vendor, Java home directory, Operating System name, and Operating System version.
The browser you are using now (if it is enabled for java) uses a JVM that runs on your workstation. Some of the system properties are set by the JVM and some are set by your browser.
These are your current JVM system properties: