


JDK (Java Development Kit), which includes JRE plus the development tools (such as compiler and debugger), is needed for writing as well as running Java programs. JRE (Java Runtime) is needed for running Java programs.

The JDK is freely available from Sun Microsystems (now part of Oracle). The Java Development Kit (JDK), officially named "Java Platform Standard Edition" or " Java SE", is needed for writing Java programs.
