A set is a collection where every element appears exactly once. No duplicates allowed. python numbers = {1, 2, 3, 2, 1} print(numbers) # {1, 2, 3} - duplicates removed Sets are also unordered. You can't access elements by index.
There's no "first element" or "third element" in a set. Think of a set like a bag of unique items. You can check if something is in the bag, add new items, or remove items. But you can't ask "what's in position ?"