System.Collections.Generic.ICollection<T>

Added in .NET 2.0
This is an interface for collections of objects

Add elements to the collection
Remove all the elements from the collection
Quickly identify if an element exists
Copy all the elements to an array
Get the total number of elements
Remove the first occurrence of a particular value
Check if the collection is read-only

Defines methods to manipulate generic collections

public interface ICollection<T> : IEnumerable<T>, IEnumerable