In the past, several languages have acted as lingua franca in different areas of the world, but the growth of modern communication and the development of air transport have created a demand for a single international language to cover the whole world. There are several reasons to believe that a single international language has become a practical necessity. Firstly, trade is becoming increasingly international, involving multiple partners who have mutually incomprehensible mother tongues. Secondly, there has been a huge proliferation of international organisations, such as UNICEF, the WHO and the European Union. Thirdly, scientific research, such as space and genetic research, is becoming more of an international cooperative effort. While multiway translation is technically available and sometimes practised, it is often expensive and inconvenient.