In 1972, the U.S. proclaimed a contiguous zone extending from 3 to 12 miles offshore (Department of State Public Notice 358, 37 Fed. Reg. 11906 (June 15, 1972), consistent with the 1958 UN Convention on the Territorial Sea and Contiguous Zone.
The aperture of a lens is the opening in the diaphragm that controls how much light is allowed to reach your focal plane (film or sensor). The aperture is usually rated as a fraction of the focal length, hence the f/x.y nomenclature. The wider an aperture is, the more light it allows through, and the smaller the number under f/ is.
The best way to understand aperture is to think of it as the controls for the pupil of an eye â the wider it gets, the more light it lets in. Together, the aperture, shutter speed and ISO produce an exposure. The diameter of the aperture changes, allowing more or less light onto the sensor depending on the situation.