This chapter lays a foundation of understanding of the flyrock problem — how and why the flyrock occurs and how precautions can be taken to reduce or avoid them. It illustrates and describes the mechanism of flyrock generation by the Swedish Detonic Research Foundation. Rock blasting is a careful optimization of the charge concentration needed for loosening the rock. In the 1950s through the experimental investigations, Langefors and Kihlstrom developed empirical formulae for calculating the charge weight and charge distribution required for different blasting geometries. Half-scale blasting experiments in granite indicated that, even if a very small charge was placed in the bottom part of the drillhole, flyrocks from the collar could achieve a considerable velocity. The fragment protective covering must be able to allow the detonation product gas to pass through it and is only intended to prevent small stones and loose material laying on top of the round from becoming airborne.