Types of collections in .net

Collections help to group related items together thereby increasing the code readability & maintainability.

In C#, System.Collections namespace contains the rich list of collection objects that can be used depending on the number of items, their datatypes and other factors.

Arraylist: Simple, unordered, indexed-based collection. It can contain object of any type.

SortedList: Sorted collection of name/value pair. Supports sorting.

Queue: FIFO collection. Has methods that support Queue/Enqueue from Queue List.

Stack: Contrast to Queue, stack is a LIFO collection. Has methods that support Push/Pop from stack.

Hashtable: A collection of name/value pairs of object allowing retrieval by name or index.

BitArray: Resizable collection storing boolean values. It Supports bit-wise operations like AND, OR, X-OR.

BitVector32: Supports bit-wise operations on boolean values. stores data as a single 32-bit integer.

StringCollection: Similar to ArrayList collection, but stores only string objects.

StringDictionary: Similar to Hashtable collection, but strongly typed class to have both key/value pair
to be only strings.

ListDictionary: Collection used to store small lists of objects.

HybridDictionary: Uses ListDictionary when number of items in collection is small. Switches to
Hashtable for handling large number of items.

NameValueCollection: Pretty much like StringDictionary, but allows you to store multiple values per key.