The Specialized Collections

The .NET Framework provides some specialized collections that are optimized to work on a specific type of data, or in a specific way. These non-generic collection classes are defined inside the System.Collections.Specialized namespace. They are synopsized in the following table:

Specialized Collection	Description
CollectionsUtil	A collection that ignores case differences in strings.
HybridDictionary	A collection that uses a ListDictionary to store key/value pairs when there are few elements in the collection. When the collection grows beyond a certain size, a Hashtable is automatically used to store the elements.
ListDictionary	A collection that stores key/value pairs in a linked list. It is recommended only for small collections.
NameValueCollection	A sorted collection of key/value pairs in which both the key and value are of type string.
OrderedDictionary	A collection of key/value pairs that can be indexed. (Added by C# 2.0.)
StringCollection	A collection optimized for storing strings.
StringDictionary	A hash table of key/value pairs in which both the key and the value are of type string.