The BM-8, BM-13, and BM-31 were the designations given to a large family of rocket artillery developed by the USSR during World War II, and which were collectively nicknamed 'Katyusha' in reference to a popular wartime song. The Katyushas came in three different calibers of 82-mm (BM-8), 132-mm (BM-13), and 300-mm (BM-31), whose warheads ranged in weight between 0.64 kg, 4.9 kg, and 28.9 kg. Range varied from a low of 2.8 km to up to 11.8 km. A total of 18 different combinations of launchers and vehicles were used, reflecting the ad hoc nature of their development during difficult wartime manufacturing conditions. Rail launchers, which mounted a rocket on top and underneath the rails, were the most common for 82-mm and 132-mm vehicles, whereas the heavier 300-mm vehicles used cage launchers. The most common chassis types were trucks, which included domestically-built models such as the popular ZIS-5 and -6 trucks, as well as US trucks provided via Lend-Lease such as the Studebaker and CCKW; by and large, launchers were mounted on whatever truck was available rather than having standardized chassis and launcher designs. Aside from trucks (which were the most common chassis types), Katyushas were also mounted on tracked vehicles such as the T-40 and T-50 light tanks, rail carriages (notable for carrying a massive 72-round launcher), river boats, as well as towed trailers and sleds. The Katyusha was first deployed in secret during 1941 under the NKVD but successful initial operations gradually expanded their use across the regular army. Despite their inaccuracy compared to existing field guns and howitzers, and their longer reload times, the Katyushas were very effective at saturation bombardment, proving incredibly distressing for troops on the receiving end (and highly lethal for those caught in the open). They received the nickname 'Stalin's organs' due to the similarity of the launchers to pipe organs, and prompted the development of German rocket artillery of their own later in the war. As many as 10,000 Katyushas of all types were built, and they became the basis for subsequent Soviet rocket artillery of the post-war era such as the BM-21 Grad. Following World War II, Katyushas were in action during the Korean War, the French Indochina War, as well as smaller conflicts around the world by Soviet client states.

Rocket technology that led to the development of the 'Katyusha' was begun by the Gas Dynamics Laboratory (GDL) and its successor, the Reactive Scientific Research Institute (RNII by its Russian acronym) in the 1930s under the leadership of Georgy Langemak, with some prototype launchers ready by 1938. A total of 18 different chassis and launcher combinations were used, with those mounted on ground vehicles given the BM (Boyevaya Mashina or 'combat vehicle') designation, while towed versions were designated as M. A second number indicated the model of the rocket used (8 for 82-mm, 13 for 130-mm, and 20, 30, or 31 for 300-mm) and a third number indicated the number of launchers in the system. The BM-13-16, for example, referred to a vehicle with a 132-mm, 16-round launcher. The type of vehicle was not inferred by the designation, and therefore a model like the BM-13-16 could be found using five different US-built trucks as their chassis. A total of eight different types of rockets were used, including one 82-mm, four 132-mm, and three 300-mm types, most of which were equipped with high explosive warheads. The most popular or recognizable versions of the Katyusha included the tracked BM-8-24 on T-40 or T-50 light tanks, the BM-8-36 on ZiS-5 or ZiS-6 trucks, the BM-8-48 on ZiS-6 or Studebaker US6 U3 trucks, the aforementioned BM-13-16 on multiple chassis types, and the heavy BM-31-12 also on Studebaker trucks.