Computers can understand only machine language, which consists of 1s and 0s. Programs written in high level language are not directly understood by the computer. The program code written in high level language is called source code.

To make the computer understand the program, translators are needed to convert the source code into machine understandable form called object code or machine code. For high level languages, translators like compiler and interpreter are used. A compiler converts the entire source code into machine code at once, while an interpreter translates one line at a time. Once translated, the computer can execute the code.