1string are immutable, which means you can't change an existing string.
>>>greeting = 'Hello world!'
>>>greeting[0] = 'J'
TypeError: object does not support item assignment
2The world in is a boolean operator that takes two strings and returns True if the first appears as a substring in the second. For example, the following function prints all the letters from word1 that also appear in word2:
>>>def in_both(word1, word2):
>>> for letter in word1:
>>> if letter in word2:
>>> print letter
3The relational operators work on strings.
All the uppercase letters come before all the lowercase letters