Adverbs of Frequency, or Frekvensadverb in Norwegian, are commonly used expressions to indicate how often something happens. These include words such as always (alltid), usually (vanligvis), often (ofte), sometimes (av og til), and never (aldri). They are versatile words that can be used in various parts of a sentence, but most often, they are placed before the main verb in the sentence or at the end of the sentence.