  By a "happy fractal" we mean a metric space with bounded geometry in the
sense of a doubling condition and a lot of paths of finite length, so that any
pair of points can be connected by a path whose length is less than or equal to
a constant times the distance between the two points. In these notes we
consider some examples, related notions, and other aspects of analysis on
metric spaces. This includes Lipschitz functions of some positive order and the
special class of functions known as "atoms" which are related to singular
integral operators.
