HUNG is the past tense and past
participle of the verb "to hang" most of the time. For instance, last
week you might have "hung upside down on the monkey bars" or
"hung your head in shame over a simple grammar error."
HANGED is the exception to these
forms when the verb "hang" means "to put to death by
hanging." The past tense and past participle of "hang" in this
meaning is "hanged." This is the *only* sense in which hanged is used.
For example,
"‘We will not be free from unfair competition till one of these fellows is
hanged for an example!" ~ Heart of Darkness
Random House Unabridged
Dictionary suggests that "hung" is becoming more common for all uses,
but the majority of books still agree that the standard English usages of
"hung" and "hanged" are those mentioned above.
New Fowler's Modern English
indicates that in Old English, there were two different words for hang (hon and
hangen). The use of these two words -- plus an Old Norse word hengjan -- is the
reason for the existence of two past-tense forms of the word "hang"
in today's English.
TIP: There's an old adage,
"curtains are hung and people are hanged" which may help you remember
which word to use. But in most cases, it will be HUNG.