An IEnumerable generic interface is returned from query expressions. A query expression that selects ints will be of type Enumerable, IEnumerable<T> The only thing you want is to iterate over the elements in a collection. You only need read-only access to that collection. IEnumerable interface contains an abstract member function called GetEnumerator() and return an interface IEnumerator on any success call. This IEnumerator interface will allow us to iterate through any custom collection. any element in a collection can be retrieved through its index property. But instead of element index, the IEnumerator provides two abstract methods and a property to pull a particular element in a collection. And they are Reset() , MoveNext() and Current . IEnumerable can move forward only over a collection, it can’t move backward and between the items. IEnumerable is best to query data from in-...