Can you please tell me what kind of construct in C# is this.

Code Golf: Numeric equivalent of an Excel column name

C.WriteLine(C.ReadLine() 
            .Reverse() 
            .Select((c, i) => (c - 64) * System.Math.Pow(26, i)) 
            .Sum());

Though I am new to C# (only two months exp so far), but since the time I have joined a C# team, I have never seen this kind of chaining. It really attracted me and I want to learn more about it.

Please give some insight about this.