- See: OO Class, Java Class File, Java Source Code File, Java Object.
- In the real world, you'll often find many individual objects all of the same kind. There may be thousands of other bicycles in existence, all of the same make and model. Each bicycle was built from the same set of blueprints and therefore contains the same components. In object-oriented terms, we say that your bicycle is an instance of the class of objects known as bicycles. A class is the blueprint from which individual objects are created.
- In the Java programming language, source files (.java files) are compiled into (virtual) machine-readable class files which have a .class extension. Since Java is a platform-independent language, source code is compiled into an output file known as bytecode, which it stores in a .class file. If a source file has more than one class, each class is compiled into a separate .class file. These .class files can be loaded by any Java Virtual Machine (JVM).
JVMs are available for many platforms, and the .class file compiled in one platform will execute in a JVM of another platform. This makes Java platform-independent.