A built-in collection that stores key-value pairs where keys can be any type (not just strings). Maps maintain insertion order and provide O(1) lookup. Unlike plain objects, Maps don't have prototype pollution concerns.

A built-in collection that stores unique values of any type. Duplicate values are automatically ignored. Sets provide O(1) add/delete/has operations and are useful for deduplication.

A mathematical notation that describes the upper bound of an algorithm's time or space complexity as input size grows. Common complexities from fastest to slowest: O(1), O(log n), O(n), O(n log n), O(n^2), O(2^n).