LINQ

The third installment of the C# language introduced Language Integrated Query (LINQ), a new construct of queries that can be run over object structures. LINQ is very new to the programming world and gives us a glimpse of functional programming on top of object-oriented general programming structure. LINQ also introduced a bunch of new interfaces in the form of the IQueryable interface, which introduced a number of libraries that can interact with the external world using LINQ. LINQ was boosted with the introduction of Lambda expressions and expression trees.