[2] The Soviet Music Encyclopedia says that they were "a powerful means of organization and education of the masses".
[1] The concept of "mass song" was put forth by members of the union of young composers Prokoll (Production Collective of the Students at the Moscow Conservatory).
A mass song is typically an alternating sequence of four-line stanzas and refrains in a non-sophisticated musical form which employed most common vocal register.
Typically these songs are of optimistic or heroic character, written in the form of a march.
[1] A significant number of mass songs were film soundtracks and later on TV movie soundtracks, sports songs and patriotic marches written for important anniversaries.