An "executable" is a type of computer file that contains a program capable of being run by a computer's operating system. When executed, it performs specific tasks or operations as defined by its code. Executables are commonly found in formats like .exe for Windows or .app for macOS. These files are essential for software applications, allowing users to launch programs directly. Executables can be created using various programming languages, such as .C or .Python, and are often compiled into machine code, which the computer can understand and execute efficiently.