why English is a Global language? | what are the historical reasons of English as a global language?

Definition of Global language: A language that is adopted as a common language between speakers whose native languages are different. HISTORICAL a mixture of Italian with French, Greek, Arabic, and Spanish, formerly used in the eastern Mediterranean. According to David Crystal (1997), a language achieves a global status when it develops a special role that is recognized in every country. This might seem like stating the obvious, but it is not, for the notion of ‘special role’ has many facets (Crystal 1997 Why lingua franca is useful: Lingua francas are important to human culture because they allow groups that otherwise could not communicate with each other the ability to interact, often for mutual benefit. This benefit can be economic, cultural, political, or a combination. English as a lingua franca: English has become the world's lingua franca is due to the fact that is the common language or mode of communication that enables people to understand one another regardless of their cultural and ethnical backgrounds. It makes communication a lot easier and understanding one another has become efficient. English for specific purpose : English for specific purposes (ESP) is a subset of English as a second or foreign language. It usually refers to teaching the English language to university students or people already in employment, with reference to the particular vocabulary and skills they need.