JRE, JVM, and JDK are three terms you often heard in conjunction with Java programming language, and most people either confuse them or think they all are the same. In this Java article, you will learn what is Java Run-time (JRE), what is Java Virtual Machine (JVM) and what is Java Development Kit (JDK) along with the Just in Time compiler or JIT. Once you know what JRE, JVM or JDK means you can differentiate them easily by yourself. This article is in continuation of the Essential JVM options which every Java programmer should know. If you haven't read those articles, you can also read them as well.