Pronunciation of v in German

The pronunciation of $⟨v⟩$ is one of the few cases of ambiguity in German orthography. The German language normally uses $⟨f⟩$ to indicate the sound (as used in the English word fight) and $⟨w⟩$ to indicate the sound  (as in victory). However, $⟨v⟩$ does occur in a large number of German words, where its pronunciation is in some words but  in others.

Originally, in Middle High German, the sound had been voiced in some dialects and was therefore written $⟨v⟩$. Contemporary German has gone back to the unvoiced pronunciation, but idiosyncratically sometimes retained the medieval spelling. As a general (and defective) rule, it can thus be said that $⟨v⟩$ is pronounced in originally German words and  in words of foreign origin.

Rules
$⟨v⟩$ is pronounced
 * in the name of the letter ;
 * in the frequent prefix ver- and all words constructed with it, such as vergessen, Vertreibung etc.;
 * in the following words and all their derivations: Vater "father"; Veilchen, Veigerl "viola flower"; Veitstanz (the neuropathy St Vitus Dance); Vers* "verse"; Vesper* "snack, small meal, evening prayer service"; Vest, Veste "(in geographical names) fortress"; Vettel "(pejorative) old woman"; Vetter "male cousin"; Viech "(pejorative) animal"; Vieh "livestock"; viel "much, many"; vier "four"; Vize* "vice-, deputy"; Viztum "historic government official; (today humorously) sub-agent"; Vlies "raw wool, fleece"; Vogel "bird"; Vogt "historic rural administrator, reeve"; Volk "folk, nation"; voll "full"; von "of, from"; vor "before, in front of"; Frevel* "outrage, sacrilege"; (the words with * are pronounced by some speakers with, especially in Austria)
 * in the following given names: Eva, Veit, Veltin, Volbrecht and all those beginning with Volk-, such as Volker;
 * at the beginning of German family and place names, apart from names of foreign descent and few exceptions (this often leads to mispronunciations among English-speakers, who falsely use in names like Vettel);
 * at the beginning of Dutch family and place names; word-initial $⟨v⟩$ is actually traditionally pronounced in Dutch, although  is currently very common in the northern varieties, found in the Netherlands;
 * at the end of words, e. g. Nerv "nerve" (its forms and derivatives are also usually pronounced with : Nerven, nervös), naiv "naïve" (this word follows the rule of final obstruent devoicing, its forms and derivatives have : Naive, Naivität), brav "brave" (its forms are pronounced with either or : brave).

$⟨v⟩$ is pronounced (or )
 * where it occurs in the middle of a word stem, usually following the stressed vowel, as in Leverkusen, but also in November (sometimes pronounced with in Austria and Switzerland) (however, exceptions to this rule are some place names, most prominently Hannover );
 * at the beginning of words and given names other than those listed above, such as Vakuum, vage (all of which are of foreign descent, mostly Latin or French, and most especially loanwords of English origin);
 * in family and place names which are neither German nor Dutch.

Pronunciation varies between and
 * in the words Evangelium "gospel" and Pulver "powder", where both alternatives may be considered standard;
 * in the words Larve "larva" and Nerven "nerves", where is the standard form and  is used only by few speakers;
 * in a number of words, such as Vikar "vicar", Viper "viper", Vitrine "closet, cabinet", where is the standard form and  is used only by few (mostly less-educated) speakers.