In Python, what happens when using list slicing: is a shallow or deep copy of the original list created?

In Python, when using list slicing, a shallow copy of the list is created. This means a new list object is created, but the elements inside refer to the same objects as in the original list.

Example:

original = [[1, 2], [3, 4]]
slice_copy = original[:]
slice_copy[0].append(99)
print(original)  # Will output [[1, 2, 99], [3, 4]]

Because it is a shallow copy, modifications inside nested objects are reflected in the original list.