Soccer, more commonly known as football outside the US, but officially called association football, is the football game played over most of the world. But of course much less in America. Still Randall makes some references directly to either soccer of the ball itself (as in 1507: Metaball where it is such a ball they are using).
In Thing Explainer the explanation about Playing fields shows the pitch/field for seven different sports including the four that have their own category, American football, soccer, baseball and basketball. The other three sport included are tennis, ice hockey and volleyball.