In linguistics, vowel length is the perceived or actual duration of a vowel sound when pronounced. Vowels perceived as shorter are often called short vowels and those perceived as longer called long vowels.
On one hand, many languages do not distinguish vowel length phonemically, meaning that vowel length alone does not change the meanings of words. However, the amount of time a vowel is uttered can change based on factors such as the phonetic characteristics of the sounds around it: the phonetic environment. An example is that vowels tend to be pronounced longer before a voiced consonant and shorter before a voiceless consonant in the standard accents of American and British English.