Time zones are a social construct. They don’t exist in any real sense, but are convenient for coordinating activities in regions where noon occurs at about the same time (that is, the sun is highest in the sky at about the same time). Standardized time zones occur in multiples of hours (with the occasional 30 or 45 minute difference) from Greenwich Mean Time also known by its official name, Coordinated Universal Time (aka UTC). Time zones are usually notated as UTC+d where d is the time difference between the time zone and UTC. For instance, UTC+0:00 contains Liberia, Ghana, Greenland, Portugal, Iceland, Ireland and the UK, UTC+3:30 contains Iran, UTC+4:30 contains Afghanistan, UTC+8:45 contains part of Western Australia, and UTC+12:00 contains New Zealand. UTC+D means that a location is D hours ahead of UTC, while UTC-D means that the location is D hours behind UTC. For instance, Brazil, Argentina and Suriname are in UTC-3:00, United States Eastern Time is UTC-5:00, United States Pacific Time is UTC-8:00 and the outlying Baker Island is in UTC-12:00.