Visual system

The visual system is the part of the central nervous system which gives organisms the ability to process visual detail, as well as enabling the formation of several non-image photo response functions. It detects and interprets information from visible light to build a representation of the surrounding environment. The visual system carries out a number of complex tasks, including the reception of light and the formation of monocular representations; the buildup of a nuclear binocular perception from a pair of two dimensional projections; the identification and categorization of visual objects; assessing distances to and between objects; and guiding body movements in relation to the objects seen. The psychological process of visual information is known as visual perception, a lack of which is called blindness. Non-image forming visual functions, independent of visual perception, include the pupillary light reflex (PLR) and circadian photoentrainment.

Structure

This article mostly describes the visual system of mammals, humans in particular, although other "higher" animals have similar visual systems (see bird vision, vision in fish, mollusc eye, reptile vision). In the case of mammals (including humans), the visual system consists of:

Windows Live Messenger

Windows Live Messenger (formerly MSN Messenger) is a discontinued instant messaging client developed by Microsoft for Windows, Xbox 360, BlackBerry OS, iOS, Java ME, S60 on Symbian OS 9.x, and Zune HD. It connected to the Microsoft Messenger service while also having compatibility with Yahoo! Messenger and Facebook Messenger. The client was first released as MSN Messenger on July 22, 1999, and was marketed under the MSN branding until 2005 when it was rebranded under Windows Live and has since been officially known by its present name, although its previous name was still used colloquially by most of its users. In June 2009, Microsoft reported the service attracted over 330 million active users each month, placing Messenger among the most widely used instant messaging clients in the world.

Following the acquisition of Skype Technologies in May 2011, Microsoft added interoperability between Skype and Microsoft accounts, allowing Skype (which had features unique to its platform and a wider user base) to communicate with Messenger contacts. In 2013, Windows Live Messenger was discontinued and Microsoft began ceasing service to existing clients. The service in China remained active for another 18 months, and ceased operations on October 31, 2014.