Why does List<T> implement so many interfaces?

List<T> derives from the following interfaces:

public class List<T> : IList<T>, ICollection<T>, IEnumerable<T>, IList, ICollection, IEnumerable

I just wonder, why it needs all these interfaces (in the class declaration)?

IList itself already derives from ICollection<T>, IEnumerable<T> und IEnumerable.

So why is the following not enough?

public class List<T> : IList<T>, IList

I hope you can solve my confusion.