JVM (Java Virtual Machine): JVM(Java Virtual Machine) acts
as a run-time engine to run Java applications. JVM is the one that actually calls the main method present in a Java code.
JVM is a part of JRE(Java Runtime Environment).
JRE (Java Runtime Environment): JRE refers to a runtime environment in which Java bytecode can be executed. It implements the JVM (Java Virtual Machine) and provides all the class libraries and other support files that JVM uses at runtime. So JRE is a software package that contains what is required to run a Java program. Basically, it’s an implementation of the JVM which physically exists.
JDK(Java Development Kit): It is the tool necessary to compile, document and package Java programs. The JDK completely includes JRE which contains tools for Java programmers. The Java Development Kit is provided free of charge. Along with JRE, it includes an interpreter/loader, a compiler (javac), an archiver (jar), a documentation generator (javadoc) and other tools needed in Java development. In short, it contains JRE + development tools.