Linq to Objects

The phrase, LINQ to Objects, refers to the use of LINQ to query in-memory data collections such as the classes in the System.Collections and System.Collections.Generic namespaces. These classes include ArrayList, List<T>, Dictionary<K,T>, and so on. You can query arrays because they implicitly support IEnumerable<T>.

You can even import a text file into enumerable data structures and run queries to filter or sort its contents.