Biochar is the solid, carbon-rich product of heating biomass with the exclusion of air (pyrolysis or “charring”). If added to soil on a large scale, biochar has the potential to both benefit global agriculture and mitigate climate change. It could also provide an income stream from carbon abatement for farmers worldwide. However, biochar properties are far from uniform, and biochar production technologies are still maturing. Research is beginning to point the way toward a targeted application of biochar to soils that maximizes its benefits.