Which one to use between IList<T> and List<T>

Question

I have list of emplyoees, then which one I should use between IList and List and why? I am using C#.

In which scenario I use List and IList.

Thank you.

Answer 1

IList represent a non-generic collection for collection of objects. If you use IList you can create customized Lists and use advantages of DIP (Dependency Inversion Principle) of OOP.

SimpleList<T> : IList<T>
{
    ...
} 

IList<T> list1 = new List<T>();
IList<T> list2 = new SimpleList<T>();

You behave same with these two kind of lists.