0-0

0-0 or O-O may refer to:

• Emoticon for a person who wears glasses
• An informal instruction to watch the conductor of an orchestra, seen in orchestral parts
• Kingside castling in chess notation
• Love all, a '0-0' (zero-zero) score in tennis, and less commonly in badminton
• Object Oriented Programming, a style of modern computer programming
• A surrogate for ∞, the infinity symbol

See also

• 00 (disambiguation)
• Zero Zero (disambiguation)
• Love All (disambiguation)
• "Nothing from Nothing", a song