This document is one of many written to inform non-specialists about some of the science behind the work of Dstl. Working with a senior scientist I gave these little booklets a graphic form of their own. This changed to its current form during a brand refresh. The team behind 'Crumbs!' supplied text and images. The tone of these booklets was always intended to be lighthearted and the team appreciated my willingness to go along with it. This, and many other titles, is available on www.gov.uk.