How can I capitalize the first letter of each word in a string?

The .title() method of a string (either ASCII or Unicode is fine) does this:

>>> "hello world".title()
'Hello World'
>>> u"hello world".title()
u'Hello World'

However, look out for strings with embedded apostrophes, as noted in the docs.

The algorithm uses a simple language-independent definition of a word as groups of consecutive letters. The definition works in many contexts but it means that apostrophes in contractions and possessives form word boundaries, which may not be the desired result:

>>> "they're bill's friends from the UK".title()
"They'Re Bill'S Friends From The Uk"

The .title() method can't work well,

>>> "they're bill's friends from the UK".title()
"They'Re Bill'S Friends From The Uk"

Try string.capwords() method,

import string
string.capwords("they're bill's friends from the UK")
>>>"They're Bill's Friends From The Uk"

From the Python documentation on capwords:

Split the argument into words using str.split(), capitalize each word using str.capitalize(), and join the capitalized words using str.join(). If the optional second argument sep is absent or None, runs of whitespace characters are replaced by a single space and leading and trailing whitespace are removed, otherwise sep is used to split and join the words.