What is the .class file???

Answer 1

.class file is a file that is created after you have compiled your code and after that a .class file is generated and inside contains bytecode that is only knowable by the java virtual machine JVM.
Java is platform independent this means the code you compile is turned to bytecode then after bytecode the JVM turns bytecode to machine language based on the platform that your computer works so this makes java platform independent.
in C++ after compiling a .exe file is created that is understandable only by the windows platform

Answer 2

A Java class file is a file (with the .class filename extension) containing Java bytecode that can be executed on the Java Virtual Machine (JVM). A Java class file is produced by a Javacompiler from Java programming language source files (.java files) containing Java classes.