Let's take a look at the code again:
books = [
'Sound of Steel',
books.sort() was used to sort the books list alphabetically. After this operation, the books variable was permanently modified, and we got a sorted list. This kind of operation, which modifies the original data structure without any helper data structure, is called an in-place operation.
sort() is an in-place function because it directly modifies a list and does not need additional memory (additional data structures) to do so.
sort() only works for lists. Dictionaries and sets are unordered, so we can't sort them. In turn, tuples are immutable, so we can't modify them.