Book excerpt: Mobile Multi-hop Ad Hoc Networks are collections of mobile nodes connected together over a wireless medium. These nodes can freely and dynamically self-organise into arbitrary and temporary, "ad-hoc" network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, (e.g., disaster recovery environments). The aim of this book is to present some of the most relevant results achieved by applying an experimental approach to the research on multi-hop ad hoc networks. The unique aspect of the book is to present measurements, experiences and lessons obtained by implementing ad hoc networks prototypes.