RIN may refer to:

• Rassemblement pour l'Indépendance Nationale, a former Quebec nationalist group
• Relative Intensity Noise, a noise term in fiber-optic communication
• Renewable Identification Number, a serial number assigned to a batch of biofuel for the purpose of tracking
• Royal Indian Navy, The naval force of British India

Rin may refer to:

• ,  yen, former Japanese currency
• Rin (given name)
• "Rin", an alternate name for the Rhine River, as in the place Am Rin
• Rin gong, a Japanese singing bowl
• RIN: Daughters of Mnemosyne, an anime
• Rin!, a Japanese manga comic
• Rin', a Japanese pop group active from 2003 to 2009
• rin(), one representation of the functional square root of sin()

is a Japanese manga written by Satoru Kannagi and illustrated by Yukine Honami. It is licensed in North America by Digital Manga Publishing, which released the manga between October 25, 2006, and April 25, 2007. It is licensed in German by Carlsen Verlag.