What does JVM and JAR specify?

Answer 1

Although this may go slightly beyond your question these are still related.

0) JVM : Java Virtual Machine
1) JRE : Java Runtime Environment
2) JDK : Java Development Kit
3) JAR : Java Archive

0) The JVM is the "interpreter" for your Java program.

1) The JRE is a more general term referring to the software needed to run Java programs such as the JVM.

2) The JDK is similar in scope to the JRE but it is a suite of tools and resources for developing Java programs.

3) A JAR file is essentially an archive format that packages together all class files, resources, and metadata required for a Java program.

Answer 2

https://en.m.wikipedia.org/wiki/Java_virtual_machine

https://en.m.wikipedia.org/wiki/JAR_(file_format)