what are the most used interfaces in C#? [closed]

Answer 1

The top two in my mind have to be ones with language support:

• IEnumerable (and IEnumerable): for use with foreach and LINQ
• IDisposable: for resources requiring cleanup, used with using

Beyond that...

• IComparable and IComparer: for generalized sorting
• IEquatable and IEqualityComparer: for generalized equality
• IList and ICollection: for mutable collections
• IDictionary: for lookup collections