English is not the most widely spoken language in the world in terms of the number of native speakers--there are many more Chinese speakers than native English speakers--but Chinese is spoken little outside of Chinese communities, so English is the most widespread language in the world. It is difficult to estimate exactly how many English speakers there are, but according to one estimate there are more than 350,000,000 native English speakers and more than 400,000,000 speakers of English as a second language (a language used in everyday life, even though it is not the native language) or foreign language (a language studied but not used much in everyday life).
However, even these numbers do not really indicate how important English is as a world language, because less than fifteen percent of the world population uses English. The importance of English is not just in how many people speak it but in what it is used for. English is the major language of news and information in the world. It is the language of business and government even in some countries where it is a minority language. It is the language of maritime communication and international air traffic control, and it is used even for internal air traffic control in countries where it is not a native language. American popular culture--primarily movies and music--carries the English language throughout the world.