This is a series of writeups intended as a guide and introduction to the German language. It's not a dictionary, nor is it a guide to modern idiom. Most of it concerns grammar and the basics of the language. Partly it doesn't go into idiom because I'm not familiar with enough with it, and partly because it might otherwise get too long. I mention some further points in my contribution to German has horrible grammar.
I've split this into six writeups:
A guide to German pronunciation
A guide to German nouns
A guide to German verbs
A guide to German adjectives and adverbs
A guide to German pronouns
A guide to German word order
Gorgonzola has already covered all that is worth knowing on prepositions, so I haven't written a section on those.
I'm not a native speaker, or a teacher, but I feel I know the language well enough to do this properly. If you are a native speaker - or indeed if you're not - I would very much welcome your suggestions and corrections. If you want to add your own section on contemporary German idiom, slang, or anything else that would be suitable, feel free.
Alternatively, if you're an editor or god and think I should structure this differently or something, tell me.
A little context: German is a Germanic language (honestly) in the West Germanic branch of the family, alongside English and Dutch. It has something like 100 million native speakers, mostly in Germany and Austria but also Switzerland, and as an unofficial language in nearby countries including Belgium, Hungary and Poland, and in pockets of South America.
It is not the closest relative of English; that is Frisian, and Dutch is also more closely related. Nevertheless it contains a wealth of vocabulary similar to English in meaning, although the two are not mutually comprehensible. Examples of German words with obvious meanings are Hand, Haus, Bier, singen, and beginnen. English and German descend from a common ancestor, the Germanic languages spoken in north-west Germany and Denmark by the Angles, Saxons and Jutes as they began their slow takeover of England in the fifth century AD. Another language closely related to German is Yiddish, which is a Germanic and not, as might be expected, a Semitic language.
German grammar is notorious for its complexity among speakers of less inflected European languages, as to convey meaning it uses word endings more, and word order less, than languages such as English, French and Italian.
Since posting this I've noticed a lot of other writeups on German, some overlapping with what I've covered, some going over other things like basic vocabulary. Some time soon I'll try to find everything there is on German and collect the links here; alternatively someone might want to make a German language metanode.