jdk: Java Development Kit is a java development tool for developers
jre: Java Runtime Environment, which is the java runtime environment, users only need to install jre
The operating environment and the development environment include five parts: core API, integration API, user interface API, publishing technology, and java virtual machine
The development environment also includes the compiler javac command for compiling Java programs and other related instructions
jvm: Java Virtual Machine, java virtual machine, is a virtual computer that runs all java programs, and is the operating environment of java. The java code we write runs on the JVM.
This is the so-called "compile once, run anywhere"