German is a Germanic language spoken by approx. 95 million people primarily in the European countries of Germany, Austria and Switzerland.
Standard German began to emerge around the 16th century, with Martin Luther’s translation of the Bible being a particularly significant development. It was based largely on the Central German dialect of Upper Saxony, on the basis that this was already a fairly influential dialect and it was located midway between some fairly diverse dialects (even then). Until 1800, it was almost entirely a written language, but then it began to be a spoken one and became especially widespread (and even dominant) with the introduction of universal schooling, where it was the language of instruction. Standard German is today a pluricentric language, with separate (but similar) German, Austrian and Swiss standards. One difference I know of is that where Germany’s standard uses the grapheme ß for a “double S”, the Swiss standard prefers ⟨ss⟩.
German is also known, though, for the wide diversity of its dialects, which I wrote more about at West Germanic languages because honestly they’re a closely related bundle of languages, rather than actually dialects of German (as they’re not all mutually intelligible, especially the Low German ones which are more closely related to English than German). In parts of the German-speaking world, including Austria and the German-speaking parts of Switzerland, a situation of diglossia exists where people switch between their native dialect and Standard German depending on the situation, but with their native dialect overwhelmingly used in ordinary life. In other parts (like around Hanover), the local dialect has virtually disappeared and everyone uses Standard German pretty much all the time. Then there’d be other places that fall somewhere between those two extremes, of course. Standard German by itself is estimated to have 76 million native speakers.
Standard German is known as one of the most conservative of the Germanic languages, at least grammatically, still retaining (for example) three noun genders and four noun cases. Phonetically, the High German consonant shift goes a long way to explaining and describing the various sound correspondences between Standard German (and High German dialects) and the rest of the Germanic branch. Word-final consonants often devoice if they weren’t devoiced already, but this isn’t reflected in the spelling.
Standard German has 15 different vowel phonemes and four diphthongs. Their rhotic consonant is usually pronounced as a uvular fricative, like in French (there’s a lot of regional variation though), but where ⟨r⟩ follows a vowel it often de-rhotacises and becomes the vowel /ɐ/ instead. This feature reminds me a bit of the Transatlantic accent of English, which does much the same thing.