a data structure that provides couple of major improvements when compared with others, like linked list, or basic array

a lookup structure which aims to make finding a particular item more efficient

an associative array, one whose elements are indexed by a key value rather than by an ordinal index

an efficient form of Dictionary which relies on a hashing function, which generates an integer hash code for each key and uses standard hashing techniques to ensure speedy access

an unbounded array where each element is identified with a unique key

a storage array of items, each representing a key/value pair

a table containing key and value pairs

class yes a Map, a synchronised HashMap. Allows unordered lookup by key, usually a String. Note, this is spelled Hashtable not HashTable.

An object that is like a dictionary or an associative array. A hashtable stores and retrieves elements using key values called hashcodes. See hashcode.