An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

Operation Anaconda took place in early March 2002 in which the United States military and CIA Paramilitary Officers, working with allied Afghan military forces, and other North Atlantic Treaty Organization and non NATO forces attempted to destroy al-Qaeda and Taliban forces in the Shahi-Kot Valley and Arma Mountains southeast of Zormat...

The 1978 South Lebanon conflict was an invasion in Lebanon up to the Litani River carried out by the Israel Defense Forces in 1978. It was a military success for the Israeli Defense Forces, as PLO forces were pushed north of the river...

Operation Market Garden was an unsuccessful Allied military operation, fought in the Netherlands and Germany in the Second World War. It was the largest airborne operation up to that time....

The movement against US involvment in the in Vietnam War began in the United States with demonstrations in 1964 and grew in strength in later years. The US became polarized between those who advocated continued involvement in Vietnam, and those who wanted peace. Peace movements consisted largely of college and graduate students, and mothers, as well as anti-establishment "hippies"...

The Orange Free State was an independent Boer republic in southern Africa during the second half of the 19th century, and later a British colony and a province of the Union of South Africa. It is the historical precursor to the present-day Free State province...

In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern boundaries, respectively...

The Organization for Security and Co-operation in Europe is the world's largest security-oriented intergovernmental organization. Its mandate includes issues such as arms control, human rights, freedom of the press and fair elections...

Orissa , officially Odisha since Nov 2011, is a state of India, located on the east coast of India, by the Bay of Bengal. It is the modern name of the ancient nation of Kalinga, which was invaded by the Maurya Emperor Ashoka in 261 BC. The modern state of Orissa was established on 1 April 1936, as a province in India, and consists predominantly of Oriya speakers...

Orlando is a city in the central region of the U.S. state of Florida. It is the county seat of Orange County, and the center of the Greater Orlando metropolitan area. According to the 2010 US Census, the city had a population of 238,300, making Orlando the 79th largest city in the United States...

is a city in the Kansai region of Japan's main island of Honshu, a designated city under the Local Autonomy Law, the capital city of Osaka Prefecture and also the biggest part of Keihanshin area, which is represented by three major cities of Japan, Kyoto, Osaka and Kobe...

Osama bin Mohammed bin Awad bin Laden was the founder of the militant Islamist organization Al-Qaeda, the jihadist organization responsible for the September 11 attacks on the United States and numerous other mass-casualty attacks against civilian and military targets...

Oscar II , baptised Oscar Fredrik was King of Sweden from 1872 until his death and King of Norway from 1872 until 1905. The third son of King Oscar I of Sweden and Josephine of Leuchtenberg, he was a descendant of Gustav I of Sweden through his mother.-Early life:At his birth in Stockholm, Oscar Fredrik was created Duke of Östergötland...

Oscar Fingal O'Flahertie Wills Wilde was an Irish writer and poet. After writing in different forms throughout the 1880s, he became one of London's most popular playwrights in the early 1890s...

Oslo is a municipality, as well as the capital and most populous city in Norway. As a municipality , it was established on 1 January 1838. Founded around 1048 by King Harald III of Norway, the city was largely destroyed by fire in 1624. The city was moved under the reign of Denmark–Norway's King Christian IV...

Otho , was Roman Emperor for three months, from 15 January to 16 April 69. He was the second emperor of the Year of the four emperors.- Birth and lineage :...

Ottawa is the capital of Canada, the second largest city in the Province of Ontario, and the fourth largest city in the country. The city is located on the south bank of the Ottawa River in the eastern portion of Southern Ontario...

The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

The Ottoman Turks were the Turkish-speaking population of the Ottoman Empire who formed the base of the state's military and ruling classes. Reliable information about the early history of Ottoman Turks is scarce, but they take their Turkish name, Osmanlı , from the house of Osman I The Ottoman Turks (or Osmanlı Turks) were the Turkish-speaking population of the Ottoman Empire who formed the base of the state's military and ruling classes. Reliable information about the early history of Ottoman Turks is scarce, but they take their Turkish name, Osmanlı (corrupted in European languages as "Ottoman"), from the house of Osman I The Ottoman Turks (or Osmanlı Turks) were the Turkish-speaking population of the Ottoman Empire who formed the base of the state's military and ruling classes. Reliable information about the early history of Ottoman Turks is scarce, but they take their Turkish name, Osmanlı (corrupted in European languages as "Ottoman"), from the house of Osman I (reigned ca...