Performing Set Operations with LINQ

LINQ’s set operations provide an easy (and fast!) way to filter or combine collections of objects in .NET. The four extension methods that perform set operations – Distinct, Except, Intersect, and Union – are available through the IEnumerable<T> and IQueryable<T> interfaces and use an instance of IEqualityComparer<T> to produce a result based on the presence or absence of equivalent elements.