A set is an unordered collection of unique elements. I use sets mostly for membership testing and removing duplicates. For example, when cleaning a large dataset, I converted a list to a set to remove duplicates instantly:
filename.python
unique_items = set(items)
The biggest difference from a list is that sets don’t preserve order and don’t allow duplicates. Also, sets are much faster for membership tests (in checks) due to hash-based implementation.
A challenge is that you cannot index sets because they are unordered, and they can’t store mutable items like lists. A limitation is no deterministic order. Alternatives include lists when order matters, or OrderedDict if uniqueness + order are both needed.