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The '''Global Positioning System''' ('''GPS'''), originally '''Navstar GPS''',<ref>(1) "GPS: Global Positioning System (or Navstar Global Positioning System)" Wide Area Augmentation System (WAAS) Performance Standard, Section B.3, Abbreviations and Acronyms.<br />(2) {{cite web |url=http://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf |title=GLOBAL POSITIONING SYSTEM WIDE AREA AUGMENTATION SYSTEM (WAAS) PERFORMANCE STANDARD|archiveurl=https://web.archive.org/web/20170427033332/http://www.gps.gov/technical/ps/2008-WAAS-performance-standard.pdf|archivedate=April 27, 2017|date=January 3, 2012}}</ref> is a [[Radionavigation-satellite service|satellite-based radionavigation]] system owned by the [[United States government]] and operated by the [[United States Space Force]].<ref>{{cite web |url=http://www.gps.gov/technical/ps/2008-SPS-performance-standard.pdf |title=Global Positioning System Standard Positioning Service Performance Standard : 4th Edition, September 2008 |access-date=April 21, 2017 |archive-url=https://web.archive.org/web/20170427025348/http://www.gps.gov/technical/ps/2008-SPS-performance-standard.pdf |archive-date=April 27, 2017 |url-status=live }}</ref> It is one of the [[satellite navigation|global navigation satellite systems]] (GNSS) that provides [[geolocation]] and [[Time transfer|time information]] to a [[Satellite navigation device|GPS receiver]] anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.<ref>{{cite web|title=What is a GPS?|url=https://www.loc.gov/rr/scitech/mysteries/global.html|access-date=January 28, 2018|archive-url=https://web.archive.org/web/20180131184150/http://www.loc.gov/rr/scitech/mysteries/global.html|archive-date=January 31, 2018|url-status=live}}</ref> Obstacles such as mountains and buildings block the relatively weak [[GPS signals]].
The GPS does not require the user to transmit any data but it can be used as a pleasure tool, and it operates independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the GPS positioning information. The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone with a GPS receiver.<ref>{{cite web|url=https://www.gps.gov/systems/gps/|title=What is GPS?|date=February 22, 2021|access-date=May 5, 2021|archive-url=https://web.archive.org/web/20210506000043/https://www.gps.gov/systems/gps/|archive-date=May 6, 2021|url-status=live}}</ref>
The GPS project was started by the [[United States Department of Defense|U.S. Department of Defense]] in 1973, with the first prototype spacecraft launched in 1978 and the full constellation of 24 satellites operational in 1993. Originally limited to use by the United States military, civilian use was allowed from the 1980s following an executive order from President [[Ronald Reagan]] after the [[Korean Air Lines Flight 007]] incident.<ref>{{cite web|url=https://www.popularmechanics.com/technology/gadgets/a26980/why-the-military-released-gps-to-the-public/|title=Why the Military Released GPS to the Public|first=Juquai|last=McDuffie|date=June 19, 2017|website=Popular Mechanics}}</ref> Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS and implement the next generation of [[GPS Block IIIA]] satellites and Next Generation Operational Control System (OCX).<ref name="losangelesmil">{{cite web|url=http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18676 |title=Factsheets : GPS Advanced Control Segment (OCX) |publisher=Losangeles.af.mil |date=October 25, 2011 |access-date=November 6, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20120503181621/http://www.losangeles.af.mil/library/factsheets/factsheet.asp?id=18676 |archive-date=May 3, 2012 |df=mdy }}</ref> Announcements from Vice President [[Al Gore]] and the [[Clinton Administration]] in 1998 initiated these changes, which were authorized by the [[United States Congress|U.S. Congress]] in 2000.
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