There has been a renaissance in magnetism in the last decade or so. In the area of micromagnetics (although in the modern context it should be nanomagnetics), major breakthroughs have resulted from the development of new magnetic imaging techniques (e.g. see 1.). A powerful magnetic microscopy is magnetic force microscopy (MFM), a variant of the atomic force microscope. One of the frontiers in magnetism being pushed back is to understand the domain structure and the magnetization reversal in nanometer sized particles. As we will show at the end of this talk, the use of high resolution MFM has increased our fundamental understanding of magnetism on this length scale. First we will present a very elementary introduction to micromagnetics research and a description of MFM with a hands on demonstration of the basic principle. We will next discuss, in some detail, one of the magnetic materials we study, 50nm magnetite crystals (a magnetosome) grown in magnetotactic bacteria (this includes a video of the bacteria trying to find food at the end of the magnetic rainbow). At the end of the talk we will discuss the magnetic states and the magnetization reversal process in magnetosome chains and lithographically prepared nickel nanodots. 1. E. Dan Dahlberg and Jian-Gian Zhu, Physics Today 48, 34 April 1995.