A long-time member of mapleprimes, Gerald A. Edgar has recently posted a wonderful paper, "Transseries for beginners" up on the arXiv. It is elementary[1], but not easy, and written in a very engaging style. For those interested in the mathematics used in some of the darker corners of Maple, this is a great introduction.
[1] Elementary, in mathematics as in Sherlock Holmes novels, is a technical term meaning that very few underlying knowledge is necessary to understand it.
Comments
Elementary
Actually, there are several technical meanings of "elementary" in mathematics (see e.g. eom.springer.de/E/default.htm), and that is not one of them. The closest is in number theory, where methods that don't involve complex analysis are called "elementary".
Indeed
You are quite right that the term 'elementary' is used a lot in mathematics, and that my use is perhaps not the most common.
I should have been more precise and described it more at a meta-mathematical statement. In other words, it is really about proofs/arguments rather than about a specific piece of mathematics. This is indeed closest in spirit to the use from number theory.