When most people think of ‘guns’, they are thinking of small arms. Broadly speaking, small arms are firearms intended for use by individuals. Small arms are the primary weapons issued to military, law enforcement, and other armed security personnel, and are widely owned and used by civilians for hunting, sport shooting, and other pursuits. The key characteristics of firearms considered to be small arms are their portability (they may be transported and operated by a single individual on foot), and their calibre (less than 20 mm) (ARES, 2017; forthcoming). This chapter begins with a brief presentation of key types of small arms, addressing their history and technical development. The chapter then provides an overview of the most important physical features and markings by which these arms are identified. It also briefly examines feed devices (such as magazines), accessories, packaging, and shipping documentation, which can provide valuable information about the provenance of firearms. Ammunition for small arms is addressed in Chapter 4.