In the performing arts, front of house (abbreviated FOH) is the portion of a performance venue that is open to the public. In theatre and live music venues, it is the auditorium and foyer, as opposed to the stage and backstage areas. In theatre, the front of house manager is responsible for ticket sales, refreshments, and making sure auditorium is set out properly.
At musical gigs and concerts the FOH Engineer is the sound mixing technician that is in charge of what the music mix sounds like for the audience. In outdoor concerts the FOH tent is usually right in the middle of the audience in the centre. If you stand near the FOH tent you might hear the concert as the sound engineer is hearing it. The PA speakers facing the audience are often called the Front of House PA system.