A swing gate rotates around a vertical hinge axis. Single-leaf swings work on openings up to about 3.5 m. Wider than that and you reach for a double swing, a sliding gate, or a telescopic gate.
Two loads drive the design: dead weight (which torques the hinge stile) and wind. Heavy swing gates over about 150 kg run three hinges per leaf and a drop bolt at the leading edge to keep sag from binding the latch. Hinge offsets, stile reinforcement, and post depth are sized to hold the leading edge within plus or minus 5 mm of plumb after a year of use.
CAD60's swing-gate models compute hinge positions, drop-bolt placement, and frame member sizing from the opening width, height, and infill weight.