The macron is a diacritical mark that looks like a horizontal line placed above a vowel. This mark is used in some languages, including Latin and Japanese, to indicate a prolonged vowel sound. For example, in the romaji system for the Japanese language, the macron is used to denote elongated vowels. Thus, the word "Tōkyō" indicates that both "o" and "u" are pronounced long, which differs from the pronunciation of short vowels. Another example of the use of the macron is in Māori, where it is used to indicate prolonged vowels that can change the meaning of a word, for instance, "keke" (cake) versus "kēkē" (jaw).