Final answer:
An open house is a social gathering at a residence that is legal unless minors consuming alcohol or drugs are present.
Step-by-step explanation:
An open house is the term typically used to describe a social gathering at a residence that is legal unless minors consuming alcohol or drugs are present. By its nature, an open house involves collective behavior, which is a noninstitutionalized activity where several people voluntarily engage.
It contrasts from situations where people who share close proximity without really interacting, which is more of a characteristic of crowds in public spaces.
However, an open house is a planned social event, unlike a conventional crowd or a large group of people who gather together in a spontaneous activity that lasts a limited amount of time. Moreover, such gatherings are not akin to people who come together for a regularly scheduled event, as open houses are typically one-off events or occur irregularly.