IEnumerable, ICollection, IList and List an Overview

Category	Methods	Name Space	Inherits from	Use
IEnumerable	GetEnumerator	System.Collections		Provided read-only access to elements in that collection via iteration.
IEnumerable<T> (Type safe version)	GetEnumerator	System.Collections.Generic	IEnumerable
ICollection	1.      Defines size, enumerators 2.      Asynchronization methods for all nongeneric collections.	System.Collections.ICollection	IEnumerable	Modify the collection and care about its size.
ICollection<T>	Defines methods to manipulate generic collections.	System.Collections.Generic.ICollection	IEnumerable<T>
IList	1.      Adding/  removing elements 2.      Clear the collection. 3.      Handle  positioning of the elements 4.      Provides an object indexer to allow the user to access the collection  eg myList[elementIndex]	System.Collections	ICollection	Modify the collection and ordering and / or positioning of the elements in the collection.
IList<T>	Some new methods for accessing a collection with specific positioning are present.	System.Collections.Generic	ICollection<T>
List	Dynamically resize arrays	System.Collections	IList	Ideal for linear collections not accessed by keys
List<T>	1.      Add  items 2.      Use an equality comparer 3.      accepts null as a valid value for reference types   4.      Allows duplicate elements. 5.      Type safe than ArrayList	System.Collections.Generic	IList<T>	Never have own member implementations with the concrete type List/List<T>.