The header <unordered_map> defines the class templates unordered_map and unordered_multimap; the header <unordered_set> defines the class templates unordered_set and unordered_multiset.
The exposition-only alias templates iter_key_t, iter_val_t, and iter_to_alloc_t defined in [associative.general] may appear in deduction guides for unordered containers.