What is the meaning of "this [int index]"?

Question

In C# we have the following interface:

public interface IList<T> : ICollection<T>, IEnumerable<T>, IEnumerable
{
    T this [int index] { get; set; }
    int IndexOf (T item);
    void Insert (int index, T item);
    void RemoveAt (int index);
}

I don't understand the line

T this [int index] { get; set; }

What does it mean?

Answer 1

That is an indexer. So you can access the instance like an array;

See MSDN documentation.