Question

What's the difference between "JDK" and "JRE"?

JRE is Java Run Time Environment. The java programming language adds the portability by converting the source code to byte code version which can be interpreted by the JRE and gets converted to the platform specific executable ones. Thus for different platforms one has corresponding implementation of JRE. But JRE has to meet the specification JVM (Java Virtual Machine) Concept that serves as a link between the Java libraries and the platform specific implementation of JRE. Thus JVM helps in the abstraction of inner implementation from the programmers who make use of libraries for their programmes.
     The JDK(Java Developmental Tool kit) comes along with java libraries and JVM embedded in it. Apart from these it comes along with the utility tools for byte code compilation "javac", Executing the byte codes through java programmes through "java" and many more utilities found in the binary directory of java. Speaking practically JDK is essential for developers, which comes along with library packages to develop Software programmes. While JRE is minimal set of programmes which executes the java class files developed by the software developers.