Jin is spoken over most of Shanxi province, except for the lower Fen River valley; much of central Inner Mongolia; as well as adjoining areas in Hebei, Henan, and Shaanxi provinces. Cities covered within this area include Taiyuan, Zhangjiakou, Hohhot, Jiaozuo, and . In total Jin is spoken by roughly 45 million people.
Like all other varieties of , there is plenty of dispute as to whether Jin is a language or a dialect. See Identification of the varieties of Chinese for the issues surrounding this dispute.
The speech of Shanxi province is, alone among the various dialects of North China, unique enough to warrant the label of "language" from some linguists. This may well be due to the geographic isolation of Shanxi. The entire province is a plateau surrounded by mountains on all sides. This may well have contributed to the differences between Jin and all the dialects that surround it.
The evolution of the language in the area has made it more or less mutually unintelligible with all dialects of mainstream Mandarin, including that of neighboring Shaanxi province. However, it is not as difficult for Mandarin speakers to pick up after a period of time, compared to other varieties of Chinese such as , largely because of the grammatical and lexical similarities between Jin and Mandarin.
Jin can be divided into the following 8 subdivisions
* Bingzhou, or that spoken in central Shanxi, including Taiyuan
* Lüliang, or that spoken in western Shanxi and northern Shaanxi
* Shangdang, or that spoken in southeastern Shanxi
* Wutai, or that spoken in parts of northern Shanxi and central Inner Mongolia
* Datong-Baotou, or that spoken in parts of northern Shanxi and central Inner Mongolia
* , or that spoken in northwestern Hebei and parts of central Inner Mongolia
* Handan-Xinxiang, or that spoken in southeastern Shanxi, southern Hebei and northern Henan
Unlike most varieties of , Jin uses the final glottal stop. This is in common with many southern varieties of Chinese. Jin has also kept the entering tone, which is the tone that goes with the final glottal stop.
Jin employs extremely complex tone sandhi, or tone changes that occur when words are put together into phrases. The tone sandhi of Jin is remarkable in two ways among Chinese dialects:
* Tone sandhi rules depend on the grammatical structure of the words being put together. Hence, an adjective-noun compound may go through different sets of changes compared to a verb-object compound.
* There are tones that merge when words are pronounced alone, but behave differently during tone sandhi.
Jin readily employs prefixes such as 圪 /k??/, 忽 /x??/, and 入 /z??/, in a variety of constructions. For example:
入鬼 "fool around" < 鬼 "ghost, devil"
In addition, there are a number of words in Jin that evolved, evidently, by splitting a mono-syllabic word into two. For example:
p?? l?? < 蹦 p?? "hop"
t??? lu? < 拖 t?u? "drag"
ku?? la < 刮 kua "scrape"
x?? l?? < 巷 x?? "street"
A similar process can also be found in Mandarin , but it is especially common in Jin.
Some dialects of Jin make a three-way distinction in demonstratives.