Collection Classes (C# Programming Guide)
The .NET Framework provides specialized classes for data storage and retrieval. These classes provide support for stacks, queues, lists, and hash tables. Most collection classes implement the same interfaces, and these interfaces may be inherited to create new collection classes that fit more specialized data storage needs.
Note
Applications that target version 2.0 and later of the .NET Framework should use the generic collection classes in the System.Collections.Generic namespace, which provide greater type-safety and efficiency than their non-generic counterparts.
ArrayList list = new ArrayList();
list.Add(10);
list.Add(20);
Collection Classes Overview
Collection Classes have the following properties
Collection classes are defined as part of the System.Collections or System.Collections.Generic namespace.
Most collection classes derive from the interfaces ICollection, IComparer, IEnumerable, IList, IDictionary, and IDictionaryEnumerator and their generic equivalents.
Using generic collection classes provides increased type-safety and in some cases can provide better performance, especially when storing value types. For more information, see Benefits of Generics.