What is a CLASS File Type?
The CLASS files can be compiled from JAVA files using javac, which is included in a JVM installation. Many of them, such as Eclipse, can compile CLASS files on the fly while the developers write the program code.
Since there are several versions of the JVM (e.g., 1.4; 1.5; 1.6), some CLASS files may not be compatible with certain versions of the JVM. It can run CLASS files, but it cannot compile them because it does not include the javac binary.
Sun Microsystems, the first Java developer, was acquired by Oracle. JRE and JVM are often used as synonyms for the-platform running Java applications.