Find the focus distance that maximises depth of field. Focus here and everything from half that distance to infinity is acceptably sharp.
Focus at the hyperfocal distance and everything from half that distance to infinity is acceptably sharp. It is the focus setting that maximises depth of field, widely used in landscape photography. H = f squared / (N times c) + f.
It is the closest distance you can focus at while keeping the background at infinity acceptably sharp. Focusing there gives the deepest possible depth of field: everything from half the hyperfocal distance out to infinity looks sharp.
H = f squared / (N times c) + f, where f is the focal length in mm, N is the f-number and c is the circle of confusion for your sensor. A wider lens or a smaller aperture brings the hyperfocal distance closer.
Setting focus to the hyperfocal distance maximises front-to-back sharpness in one shot, which is ideal for scenes with a near foreground and a distant horizon.