J2SE 1.2 (JDK 1.2) (December 1998): Re-branded as 'Java 2' and renamed JDK to J2SE (Java 2 Standard Edition).JDK 1.1 (February 1997): Introduced AWT event model, inner class, JavaBean, JDBC, and RMI.JDK 1.0 (January 1996): Originally called Oak (named after the oak tree outside James Gosling's office).JDK Alpha and Beta (1995): Sun Microsystem announced Java in September 23, 1995.Since you are supposed to write Java Programs, you should install JDK, which includes JRE. JDK (Java Development Kit), which includes JRE plus the development tools (such as compiler and debugger), is need 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.