This document discusses the various functions and roles of the English language. It begins by defining language and its purpose of communicating ideas. It then outlines the main functions of a language as instrumental, regulatory, interactional, and personal. Additionally, English serves as an international language, a link language that facilitates mobility between countries, a library language for accessing knowledge, a window onto other cultures of the west and east, a language for employment, trade, and science/technology. The document emphasizes how English has become a global language due to its widespread use in these many domains.