Forensic science is the application of science to the law. Because of its connections to crime and detective work, it is a subject of wide fascination. A criminal case can often hinge on a piece of evidence such as a hair, a blood trace, half a footprint or a tyre mark. High profile cases such as the Lawrence enquiry, and the present Madeleine McCann case have enhanced this interest in recent years. Modern techniques, especially DNA fingerprinting, are often in the news. This Very Short Introduction looks at the nature of forensic science, how forensic scientists work, the different techniques involved, and the broader legal issues. Examples will be given from cases in the UK, US, and other countries to highlight particular techniques and challenges.