A CXX file is a source code file written in the C++ programming language. It contains human-readable code that defines the structure and behavior of a program. This code is typically compiled into machine-executable code by a C++ compiler. CXX files can contain class definitions, function implementations, variable declarations, and other programming constructs. They are essential for developing software applications, operating systems, and other types of programs. C++ is a powerful and versatile language widely used in various domains, including game development, system programming, and high-performance computing. The CXX extension is often used interchangeably with .CPP, .CC, and .HPP, although conventions may vary between projects and compilers. These files are plain text and can be edited with any text editor, but specialized IDEs (Integrated Development Environments) provide features like syntax highlighting, code completion, and debugging tools to enhance the development process.