These are the collection that can hold elements of different data types.
C# includes a Queue collection class in the System.Collection namespace.
C# includes a special type of collection which stores elements in LIFO style (Last In First Out)
HashTable stores data in key/value format. Array and ArrayList also stores data in key/value format.
A common use of JSON is to exchange data to/from a web server. When sending data to a web server, the data has to be a string.