Pressures on the global environment in recent times and the elimination of fossil fuel resources are the core motive behind the frequent utilization of alternative resources of energy instead of conventional means. The transformation of biomass material into an appropriate form of energy and fuel through air gasification is an appropriate option. Gasification is an exclusive and promising technology that can be functioned as a simple and erudite system such as fixed bed gasifiers or moving bed technology. This chapter provides up-to-date information on different types of gasifiers used in air gasification of biomass and their product potentials. The research advancement in the fixed and fluidized bed gasifiers and their subcategorized reactors are discussed here to enlighten their application, merits, and demerits. Some deductions and forthcoming views regarding gasification technologies are also presented. © 2022 Elsevier B.V. All rights reserved.