LINQ is made possible using Expression Trees but the query itself is not expression tree. Read this article, it will give you a good head start. http://blogs.ms

LINQ is made possible using Expression Trees but the query itself is not expression tree. Read this article, it will give you a good head start. http://blogs.msdn.com/charlie/archive/2008/01/31/expression-tree-basics.aspx http://blogs.msdn.com/charlie/archive/2008/01/31/expression-... Also, your understanding of his point is valid and I agree with it, I did mention that in my original comment. I was acting pedantic about terminology. And I did not question the advice of using StringBuilder when concatenating strings in a loop, I questioned the advice to use string.Format instead of using '+' operator.