Do can refer to:

1. In English, do is a verb whose use as an auxiliary verb is often grammatically required for negation and for interrogative sentences.
2. The Chinese character 道 (Pinyin: dào; Wade-Giles: tao⁴), which is pronounced dō in Japanese and do (도) in Korean. It means "road," "way," "Daoism," "province," and "circuit."
   1. In Korea, Do is the designation for "province," as in Gyeonggi-do (경기도; 京畿道). See Provinces of Korea.
   2. In Japan, Dō means "circuit," when used in the name of Hokkaido (北海道) prefecture. See Prefectures of Japan.
   3. In Japan, the character also means "road," as in Tokaido (東海道) and Nakasendo (中山道).
   4. It is used as a suffix for various arts and implies that they are not just techniques but have spiritual elements. In this circumstance it is usually translated as "the way of." For example, Japanese tea ceremony is called "Sado" (茶道) and flower arrangement is called "Kado" (華道), these translate to "the way of tea" and "the way of flowers" respectively. Since the Meiji era, Japanese martial artists have adopted this suffix for names of martial arts such as Aikido, Judo and Kendo. This convention was introduced to Korea, but not to China, with martial arts themselves during the Japanese rule so that the suffix can be found in Taekwondo.
3. the Chinese character 島 (Pinyin: dǎo; Wade-Giles: tao³), which is pronounced do in Korean and means "island". It used in the names of Korean islands (e.g., Ganghwa-do (강화도; 江華島), and Ulleung-do (울릉도; 鬱陵島). Note that "Jeju-do" transliterates two distinct Korean terms: "Jeju Province" (제주도; 濟州道) and "Jeju Island" (제주도; 濟州島).
4. In Japanese martial arts, the part of the armour that protects the trunk (cuirass).
5. An Eindhoven Netherlands-born singer, most famous for singing the chorus on DJ Sammy's 2002 worldwide smash, "Heaven". Her real name is Dominique van Hulst .
6. In solfege, do is the name of the first note of the scale.
7. do is the ISO country code for the Dominican Republic.
8. The Dornier (Do) aircraft.
9. A nickname of Marshall Applewhite.
10. Denominación de Origen, a Spanish appellation.
11. Short form for the scientific concept of Dissolved Oxygen.
12. An abbreviation for the United States Central Intelligence Agency's Directorate of Operations.
13. An abbreviation for 'director of operations'.
14. An abbreviation for hairdo.
15. An abbreviation for ditto (do.), meaning "repeat the above info here".
16. In English capital letters, an informal writing of D.O., a title suffix for Doctor of Osteopathic Medicine
17. In the role-playing game Mage:_The_Ascension, Do ("the Way") is a martial art practiced by the Akashic_Brotherhood.