str.lower
Convert all letters of the string to lowercase.
Python 3.13
str.lower()Return value
A new string; the original is not changed.
Examples
Converting to lowercase
Python 3.13
print('HELLO'.lower())hello
Case-insensitive comparison
Python 3.13
answer = 'Yes'
print(answer.lower() == 'yes')True
Details
For case-insensitive comparison, str.casefold is more reliable: it handles special cases such as the German ß.