Dakuten

Dakuten (濁点?), colloquially ten-ten ("dot dot"), is a diacritic sign most often used in the Japanese kana syllabaries to indicate that the consonant of a syllable should be pronounced voiced. Handakuten (半濁点), colloquially maru ("circle"), is a diacritic used with the kana for syllables starting with h to indicate that they should instead be pronounced with . The kun-yomi pronunciation of the character 濁 is nigori; hence the daku-ten may also be called the nigori-ten. The meaning of this character—muddy or turbid—is a hint that the theory behind this kind of spelling device originally came from China, where consonant sounds were traditionally described by terms such as clear, half-clear, muddy, and so on.

In informal writing, it is occasionally used on vowels to indicate a shocked or strangled articulation.

Dakuten were used sporadically since the start of written Japanese; their use tended to become more common as time went on. The modern practice of using dakuten in all cases of voicing, in all writing, only came into being in the Meiji period.