German is a West Germanic language, thus related to and classified alongside English and Dutch. It is one of the world's major languages and the most widely spoken first language in the European Union. Around the world, German is spoken by approximately 105 million native speakers and also by about 80 million non-native speakers. Standard German is widely taught in schools, universities and Goethe Institutes worldwide. It is overall the third most learned language worldwide.

When Martin Luther translated the Bible he based his translation mainly on the bureaucratic standard language used in Saxony also known as Meißner-Deutsch . This language was based on Eastern Upper and Eastern Central German dialects and preserved much of the grammatical system of Middle High German (unlike the spoken German dialects in Central and Upper Germany that already at that time began to lose the genitive case and the preterite tense). In the beginning, copies of the Bible had a long list for each region, which translated words unknown in the region into the regional dialect. Roman Catholics rejected Luther's translation in the beginning and tried to create their own Catholic standard (gemeines Deutsch) — which, however, only differed from 'Protestant German' in some minor details. It took until the middle of the 18th century to create a standard that was widely accepted, thus ending the period of Early New High German. In 1901 the 2nd Orthographical Conference ended with a complete standardization of German language in written form while the Deutsche Bühnensprache (literally: German stage-language) had already established spelling rules for German three years earlier which were later to become obligatory for general German pronunciation.

German was the language of commerce and government in the Habsburg Empire, which encompassed a large area of Central and Eastern Europe. Until the mid-19th century it was essentially the language of townspeople throughout most of the Empire. It indicated that the speaker was a merchant, an urbanite, not their nationality. Some cities, such as Prague (German: Prag) and Budapest (Buda, German: Ofen), were gradually Germanized in the years after their incorporation into the Habsburg domain. Others, such as Bratislava (German: Pressburg), were originally settled during the Habsburg period and were primarily German at that time. A few cities such as Milan (German: Mailand) remained primarily non-German. However, most cities were primarily German during this time, such as Prague, Budapest, Bratislava (German: Pressburg), Zagreb (German: Agram), and Ljubljana (German: Laibach), though they were surrounded by territory that spoke other languages.

Until about 1800, standard German was almost only a written language. At this time, people in urban northern Germany, who spoke dialects very different from Standard German, learned it almost like a foreign language and tried to pronounce it as close to the spelling as possible. Prescriptive pronunciation guides used to consider northern German pronunciation to be the standard. However, the actual pronunciation of standard German varies from region to region. Media and written works are almost all produced in standard German (often called Hochdeutsch in German) which is understood in all areas where German is spoken.

The first dictionary of the Brothers Grimm, the 16 parts of which were issued between 1852 and 1860, remains the most comprehensive guide to the words of the German language. In 1860, grammatical and orthographic rules first appeared in the Duden Handbook. In 1901, this was declared the standard definition of the German language. Official revisions of some of these rules were not issued until 1998, when the German spelling reform of 1996 was officially promulgated by governmental representatives of all German-speaking countries. Since the reform, German spelling has been in an eight-year transitional period during which the reformed spelling is taught in most schools, while traditional and reformed spellings co-exist in the media. See German spelling reform of 1996 for an overview of the public debate concerning the reform, with some major newspapers and magazines and several known writers refusing to adopt it.

The German spelling reform of 1996 led to public controversy and considerable dispute. Some state parliaments (Bundesländer) would not accept it (North Rhine Westphalia and Bavaria). The dispute landed at one point in the highest court, which made a short issue of it, claiming that the states had to decide for themselves and that only in schools could the reform be made the official rule—everybody else could continue writing as they had learned it. After 10 years, without any intervention by the federal parliament, a major yet incomplete revision was installed in 2006, just in time for the coming school year. In 2007, some traditional spellings were finally invalidated even though they caused little or no trouble. The only sure and easily recognizable symptom of a text's being in compliance with the reform is the -ss at the end of words, such as dass and muss. Classic spelling forbade this ending, instead using daß and muß. The cause of the controversy evolved around the question of whether a language is part of the culture which must be preserved or a means of communicating information which has to allow for growth.

High German is divided into Central German and Upper German. Central German dialects include Ripuarian, Moselle Franconian, Rhine Franconian, Central Hessian, East Hessian, Lower Hessian, Thuringian, Silesian, High Franconian, Lorraine Franconian, Mittelalemannisch, North Upper Saxon, High Prussian, South Markish and Upper Saxon. It is spoken in the southeastern Netherlands, eastern Belgium, Luxembourg, parts of France, and parts of Germany approximately between the River Main and the southern edge of the Lowlands. Modern Standard German is mostly based on Central German, but it should be noted that the common (but not linguistically correct) German term for modern Standard German is Hochdeutsch, that is, High German. The Moselle Franconian varieties spoken in Luxembourg have been officially standardised and institutionalised and are therefore usually considered a separate language known as Luxembourgish.

Upper German dialects include Northern Austro-Bavarian, Central Austro-Bavarian, Southern Austro-Bavarian, Swabian, East Franconian, High Alemannic German, Highest Alemannic German, Alsatian and Low Alemannic German. They are spoken in parts of the Alsace, southern Germany, Liechtenstein, Austria, and the German-speaking parts of Switzerland and Italy. Wymysorys is a High German dialect of Poland, and Sathmarisch and Siebenbürgisch are High German dialects of Romania. The High German varieties spoken by Ashkenazi Jews (mostly in the former Soviet Union) have several unique features, and are usually considered as a separate language, Yiddish. It is the only Germanic language that does not use the Latin alphabet as its standard script.

Most German vocabulary is derived from the Germanic branch of the Indo-European language family, although there are significant minorities of words derived from Latin and Greek, and a smaller amount from French and most recently English. At the same time, the effectiveness of the German language in forming equivalents for foreign words from its inherited Germanic stem repertory is great. Thus, Notker Labeo was able to translate Aristotelian treatises in pure (Old High) German in the decades after the year 1000. Overall, German has fewer Romance-language loanwords than English.

The coining of new, autochthonous words gave German a vocabulary of an estimated 40,000 words as early as the ninth century. In comparison, Latin, with a written tradition of nearly 2,500 years in an empire which ruled the Mediterranean, has grown to no more than 45,000 words today.

Even today, many low-key non-academic movements try to promote the Ersatz (substitution) of virtually all foreign words with ancient, dialectal, or neologous German alternatives. It is claimed that this would also help in spreading modern or scientific notions among the less educated, and thus democratise public life, too. The modern German scientific vocabulary has nine million words and word groups (based on the analysis of 35 million sentences of a corpus in Leipzig, which as of July 2003 included 500 million words in total).

German was the language of commerce and government in the Habsburg Empire, which encompassed a large area of Central and Eastern Europe. Until the mid-19th century it was essentially the language of townspeople throughout most of the Empire. It indicated that the speaker was a merchant, an urbanite, not his nationality. Some cities, such as Prague (German: Prag) and Budapest (Buda, German: Ofen), were gradually Germanized in the years after their incorporation into the Habsburg domain. Others, such as Bratislava (German: Pressburg), were originally settled during the Habsburg period and were primarily German at that time. A few cities such as Milan (German: Mailand) remained primarily non-German. However, most cities were primarily German during this time, such as Prague, Budapest, Bratislava, Zagreb (German: Agram), and Ljubljana (German: Laibach), though they were surrounded by territory where other languages were spoken.

Until about 1800, standard German was almost solely a written language. At this time, people in urban northern Germany, who spoke dialects very different from Standard German, learnt it almost as a foreign language and tried to pronounce it as close to the spelling as possible. Prescriptive pronunciation guides of that time considered northern German pronunciation to be the standard. However, the actual pronunciation of standard German varied from region to region. Media and written works are almost all produced in standard German (often called Hochdeutsch in German), which is understood in all German-speaking areas (except by pre-school children in areas where only dialect is spoken, for example Switzerland — but in this age of TV, even they now usually learn to understand Standard German before school age). The first dictionary of the Brothers Grimm, which was issued in 16 parts between 1852 and 1860, remains the most comprehensive guide to the lexicon of the German language.