蒙古语是蒙古民族说的语言，属于阿尔泰语系蒙古语族。蒙古语有很多方言，主要分为中部方言、西部方言（卫拉特语）、北部方言（布里亚特语）和东部方言（科尔沁-喀喇沁）。蒙古语接近辽国的契丹语，但是由于契丹文尚未完全解读，很难进行语言历史比较。

现在中国内蒙古以传统蒙古语字母书写，而蒙古国在蒙古人民共和国时期由于苏联影响，废除了传统蒙文，主要使用西里尔字母，现已恢复使用传统蒙文，使用量较少。

为了方便，这里使用的是蒙古文的转写，这种写法代表蒙古语在13世纪的发音，与现在的方言有明显的区别。但是，从这种写法可以推断现在各种方言的读音，而进行相反的转换（从现在的发音推断古蒙古语的发音）则很困难。

The Mongolian language (in Mongolian script: , Mongɣol kele; in Mongolian Cyrillic: Монгол хэл, Mongol khel) is the official language of Mongolia and largest-known member of the Mongolic language family. The number of speakers across all its dialects may be 10 million, including the vast majority of the residents of Mongolia and many of the Mongolian residents of the Inner Mongolia Autonomous Region. In Mongolia, the Khalkha dialect, written in Cyrillic (and at times in Latin for social networking), is predominant, while in Inner Mongolia, the language is dialectally more diverse and is written in the traditional Mongolian script. In the discussion of grammar to follow, the variety of Mongolian treated is Standard Khalkha Mongolian (i.e., the standard written language as formalized in the writing conventions and in the school grammar), but much of what is to be said is also valid for vernacular (spoken) Khalkha and other Mongolian dialects, especially Chakhar.