Python set is a collection of items:
>>> symbols = {'AAPL', 'MSFT', 'NVDA'}
>>> type(symbols)
<class 'set'>
Its main difference from list and tuple is that all items must be unique – there can't be duplicates.
>>> symbols = {'AAPL', 'AAPL', 'MSFT', 'NVDA'}
>>> symbols
{'NVDA', 'MSFT', 'AAPL'}
Finding a set item by its index does not work, unlike tuples and lists.
>>> symbols[1] Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'set' object is not subscriptable