The ITU phonetic alphabet is the most widely used radiotelephone spelling alphabet. During traffic nets, and other times amateur radio operators needs to exchange information, ITU phonetics is the standard to use.
You can find out more information about ITU phonetics at Wikipedia.
Alpha
Bravo
Charlie
Delta
Echo
Foxtrot
Golf
Hotel
India
Juliet
Kilo
Lima
Mike
November
Oscar
Papa
Quebec
Romeo
Sierra
Tango
Uniform
Victor
Whiskey
X-ray
Yankee
Zulu
One
Two
Three (Tree)
Four
Five
Six
Seven
Eight
Niner
Zero