A computer program is a collection of instructions that performs a specific task when executed by a computer. A computer requires programs to function, and typically executes the program's instructions in a central processing unit. A program is like a recipe. It contains a list of ingredients (called variables) and a list of directions (called statements) that tell the computer what to do with the variables. The variables can represent numeric data, text, or graphical images. When a program is created, it is compiled to a language that the computer can understand. Once compiled the program does not need any other programs to run as long it as the computer has the required operating system and platform. A script is not compiled but needs an interpreter to translate the script into something the computer understands.