A hashtable is a data structure that lets you look up stored items USING an associated KEY. With an array, you can quickly access an element by specifying an integer index. The limitation of an array is that the look up key can only be an integer. With a hashtable, on the other hand, you can associate an item with a key and then USE the key to look up the item. You can use an object of any type as a key in a hashtable.

For example: you MIGHT specify the license-plate number as the key and use the key to look up the vehicle owner's record. To distinguish one item from the next, the associated key that you use must be unique for each item, as in the case of a vehicle's license plate number.

A hashtable is a data structure that lets you look up stored items using an associated key. With an array, you can quickly access an element by specifying an integer index. The limitation of an array is that the look up key can only be an integer. With a hashtable, on the other hand, you can associate an item with a key and then use the key to look up the item. You can use an object of any type as a key in a hashtable.

For example: you might specify the license-plate number as the key and use the key to look up the vehicle owner's record. To distinguish one item from the next, the associated key that you use must be unique for each item, as in the case of a vehicle's license plate number.