list.sort() / list.reverse() / list.copy()

# Sorts the list in place (returns None).
list.sort(key=None, reverse=False)

# Reverses the order of the list's elements in place (returns None).
list.reverse()

# Returns a shallow copy of the list.
list.copy()

# sorted() returns a new sorted list without modifying the original.
sorted(iterable, key=None, reverse=False)

sample_list_sort_reverse.py

# Sort a list in place using sort().
nums = [3, 1, 4, 1, 5, 9, 2, 6]
nums.sort()
print(nums)  # [1, 1, 2, 3, 4, 5, 6, 9]

# Sort in descending order using reverse=True.
nums.sort(reverse=True)
print(nums)  # [9, 6, 5, 4, 3, 2, 1, 1]

# Sort with a custom key function.
pilots = ["Soryu Asuka", "Ayanami Rei", "Ikari Shinji", "Nagisa Kaworu"]
pilots.sort(key=len)  # Sort by string length.
print(pilots)  # Sorted from shortest to longest string.

# Another example using a key function with sort().
names = ["Vegeta", "son goku", "BULMA", "krillin"]
names.sort(key=str.lower)  # Sort case-insensitively.
print(names)  # ['BULMA', 'krillin', 'son goku', 'Vegeta']

# Sort a list of dictionaries by a key.
students = [
    {"name": "Ayanami Rei", "score": 92},
    {"name": "Ikari Shinji", "score": 85},
    {"name": "Soryu Asuka", "score": 78},
]
students.sort(key=lambda s: s["score"])
print(students[0]["name"])  # Soryu Asuka (the lowest score)

# Reverse the order of a list using reverse().
items = [1, 2, 3, 4, 5]
items.reverse()
print(items)  # [5, 4, 3, 2, 1]

# Create a copy of a list using copy().
original = [1, 2, 3]
copied = original.copy()
copied.append(4)
print(original)  # [1, 2, 3] (the original list is unchanged)
print(copied)    # [1, 2, 3, 4]

# sorted() does not modify the original list.
nums2 = [3, 1, 4, 1, 5]
sorted_nums = sorted(nums2)
print(nums2)        # [3, 1, 4, 1, 5] (unchanged)
print(sorted_nums)  # [1, 1, 3, 4, 5] (new list)

# Sort a list of strings using sorted().
result = sorted(["Son Goku", "Bulma", "Vegeta"])
print(result)  # ['Bulma', 'Son Goku', 'Vegeta']

python3 list_sort_reverse.py
[1, 1, 2, 3, 4, 5, 6, 9]
[9, 6, 5, 4, 3, 2, 1, 1]
['Soryu Asuka', 'Ayanami Rei', 'Ikari Shinji', 'Nagisa Kaworu']
['BULMA', 'krillin', 'son goku', 'Vegeta']
Soryu Asuka
[5, 4, 3, 2, 1]
[1, 2, 3]
[1, 2, 3, 4]
[3, 1, 4, 1, 5]
[1, 1, 3, 4, 5]
['Bulma', 'Son Goku', 'Vegeta']

The key difference between sort() and sorted() is whether the original list is modified. sort() modifies the original list in place and returns None. If you try to assign the result to a new variable, it will be None. Use sorted() whenever you need to preserve the original list.

Python's sorting algorithm is Timsort, which is a stable sort — meaning elements with equal values maintain their relative order. This makes it easy to sort by multiple keys in stages (for example, first by name, then by score) and have it work as expected.

copy() creates a shallow copy of the list. If the list contains objects such as other lists or dictionaries, those objects are not copied — only references to them are shared. For a fully independent copy, use copy.deepcopy(). For slicing and concatenation of lists, see List Slicing.