The Java JDK (Java Development Kit) is a software development environment that creates Java applications.

Java is one of those things that you don’t need to download until the moment you do. Most computer users will go about their business without having to download Java for Windows.

The Java Runtime Environment (JRE) is a software package developed by Oracle Corporation. It's designed to provide a runtime environment for applications written in Java programming language.

To check which version of Java you have on your Windows computer, you'll need to open the Command Prompt.