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Sunglasses allow better vision in bright daylight, and may protect one's eyes against damage from high levels of ultraviolet light. Typical sunglasses are darkened for protection against bright light or glare; some specialized glasses are clear in dark or indoor conditions, but turn into sunglasses when in bright light. Most sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be ordered. Specialized glasses may be used for viewing specific visual information (such as stereoscopy) or 3D glasses for viewing three-dimensional movies. Sometimes glasses with no corrective power in the lenses are worn simply for aesthetic or fashion purposes. Even with glasses used for vision correction, a wide range of designs are available for fashion purposes, using plastic, wire, and other materials.
Access control is often a system enabling authorities to regulate use of areas and resources in a given physical facility or computer-based information system. Access control is, in fact, a typical, everyday phenomenon. For example, a lock on the car door is basically a type of access control. The PIN on a bank's ATM system is another form of access control. Even nightclub bouncers, browsing front of the door, are another demonstration of (perhaps) a more primitive mode of access control. Using an access control mechanism is very important when persons aim to secure confidential, important, or sensitive information and equipment.
Windows PCs can be used as general purpose computers for all those varieties of such things as writing letters, editing photos or surfing the Web. However, there's also specialized use times when the PC is supposed to be used only in a very restricted way. Imagine a public kiosk terminal which could only be utilized to allow Web browsing in order to provide usage of an individual, specialized application as being a booking system. Also terminals in museums or at exhibitions have special requirements in terms of security and functionality. In most cases the underlying os (Windows) have to be secured and locked down in a fashion that merely a predefined application can be executed understanding that the conclusion user has no further use of other applications or critical os functions.
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