As one of the six official languages used by UN (United Nations), Chinese now has earned itself greater status in the World. The official language of China is the Mandarin (Standard Chinese), which is the very name of 'Hanyu' or 'Putonghua', belonging to Sino-Tibetan.
Putonghua, standard form of modern Chinese, is a parlance in mainland China. It is the common language of all modern Han nationality people. In Taiwan Province and Hong Kong, it is called 'Guoyu' while in Singapore and Malaysia, it is often called 'Huayu'.
Mandarin Chinese is shaped and based on the Beijing dialect and other dialects spoken in the northern areas of China. Students are often taught Chinese language as 'Yuwen' in their schoolbooks. It is beyond all doubt that Chinese is the language used as a mother tongue by the most people accounting for about one fifth of the world's population. Chinese once had very great influence on some peripheral countries with their languages and characters, such as Japanese, Korean and Vietnamese.
English is a required course and universal education in China and has great popularity. Nowadays many Chinese people can speak basic English, especially the youth, students, and staff of service trades like hotels, restaurants, airlines, banks and post offices. In large cities there are more people who can communicate with foreigners in English than smaller towns & cities. Some may master a second foreign language like French, German, Japanese, Italian, and Spanish. However, in rural or remote areas, few people can speak English or other foreign languages.
The language barrier now is not a problem at all for those that wish to come to China. You can refer to the Basic Expressions in Chinese and our Learning Chinese Forum.
With a vast territory and huge population, China has many different dialects which are of great complexity. Divided into official and non-official dialects, they vary between different areas. The official dialects generally refer to the northern dialects, while the non-official dialects are often spoken in the southeast part of the country.
Due to the differences between each of the Chinese dialects, there are obvious obstacles to people speaking their own dialects and communicating with each other, especially among the non-official dialects.