Putonghua
Pǔtōnghuà
(Simplified Chinese: 普通话; Traditional Chinese: 普通話; literally "common speech").
Pǔtōnghuà, often referred to as "Mandarin Chinese" or simply "Mandarin" in English, is the official Chinese dialect of the People's Republic of China and is understood by the majority of Chinese speakers.
In Taiwan, a more commong term for pǔtōnghuà is guóyǔ (Traditional Chinese: 國語; Simplified Chinese: 国语; literally "national language"). It is also known as hànyǔ (Simplified Chinese: 汉语; Traditional Chinese: 漢語; literally: "Han (Chinese) language").
The pronunciation of pǔtōnghuà is based on the Beijing dialect of Standard Mandarin, although there are differences between the Beijing pronunciation and Standard pronunciation.
English speakers referring to "Chinese" as a language will typically refer to this dialect of Chinese.
Hànyǔ Pīnyīn is the official romanisation of pǔtōnghuà in the People's Republic of China. Taiwan typically makes use of the Wade-Giles system.