What standard container is used in the implementation of the unordered_map data structure?

In C++, the standard container used to implement the unordered_map data structure is a hash table based on a bucket array with collision chaining.

In the STL standard library, unordered_map is implemented using a hash table where keys are hashed using the std::hash<Key> function, and collisions are handled through linked lists (chains) within the buckets.

Thus, the fundamental container is a bucket array, each containing a linked list of elements with the same hash.