Can you explain how the set is implemented in Python and how it works internally?

In Python, a set is implemented as a hash table where elements are stored as keys without values. This provides fast access, addition, and removal of elements — on average in O(1) time.

Main implementation points:

• Each element must be hashable (immutable) so that its hash can be computed and its position in the table determined.
• When adding an element, its hash is computed, and the element is placed in the corresponding bucket.
• In case of collisions, open addressing or chaining methods are used (depending on implementation).
• When the load factor reaches a certain threshold, the table is resized to maintain performance.

Example of using a set:

s = set()
s.add(1)
s.add(2)
s.add(2)  # duplicate will not be added
print(s)  # {1, 2}

if 1 in s:
    print("1 is in the set")

Thus, a set efficiently stores unique elements and provides fast lookup.