An alliance is a pact, coalition or friendship between two or more parties, made in order to advance common goals and to secure common interests. It is a Political agreement between countries to support each other in disputes with other countries.
Examples of alliances 
International relations 
In international relations, the Anglo-Portuguese Alliance, signed in 1373 between the Kingdom of England (succeeded by the United Kingdom) and Portugal, is the oldest alliance in the world which is still in force.
- Holy Alliance, coalition of Russia, Austria and Prussia created in 1815
- Quadruple Alliance (disambiguation)
- Triple Alliance (disambiguation)
- North Atlantic Treaty Organization (NATO), a military alliance established by the signing of the North Atlantic Treaty
Political organizations 
- Alberta Alliance Party, a small right-wing political party in Alberta, Canada that existed from 2002 until merging to form the Wildrose Alliance Party in 2008 (see below)
- Social Democratic Alliance, political party in Iceland
- Alliance (New Zealand), left-wing political party in New Zealand
- Alliance 90, an alliance of three opposition groups in East Germany
- Alliance for Chile, a political coalition that includes Chiles two rightwing parties RN and UDI
- Alliance (Sweden), an electoral and governing (since September 2006) political coalition between the Moderate Party, Centre Party, Liberal People's Party and Christian Democrats
- Alliance Party of Northern Ireland, political party operating in Northern Ireland
- Canadian Alliance, Canadian right-of-centre conservative political party that existed from 2000 to 2003
- Fijian Alliance, a former political party in Fiji
- International Alliance of Socialist Democracy, an organization founded by Mikhail Bakunin
- Melanesian Alliance Party, a political party in Papua New Guinea
- People's Alliance for Democracy, a long-term protest movement in Thailand which is opposed to former Prime Minister Thaksin Shinawatra and his supporters
- ProLife Alliance, a political party in the United Kingdom
- SDP-Liberal Alliance, electoral alliance of the Social Democratic Party and the Liberal Party in the United Kingdom that operated from 1981 to 1988
- The Alliance Party (Malaya), the predecessor of the Barisan Nasional political coalition in Malaysia
- The Alliance (Hong Kong), former name of Professional Forum, political group in Hong Kong
- Hong Kong Alliance in Support of Patriotic Democratic Movements in China, an organisation in Hong Kong which supports democratic movements in China
- Tongmenghui (or "Revolutionary Alliance"), a Chinese underground resistance movement which operated in Japan from 1905 to 1950
- United Iraqi Alliance, a political coalition in Iraq
- United People Alliance, electoral and political coalition between the Portuguese Communist Party or PCP and the Portuguese Democratic Movement or MDP
- National Alliance (disambiguation), several political parties
- National Democratic Alliance (disambiguation), several political parties
- New Alliance Party (disambiguation), several political parties
- Wildrose Alliance Party, a small right-wing political party in Alberta, Canada
- Liberal Alliance (disambiguation), several political parties
- The Alliance short for Republican, Ecologist and Social Alliance (ARES) is a federation of centrist political parties in France.
Television, film, and comic books 
- The Alliance, a group of aliens and monsters in the Doctor Who episode 'The Pandorica Opens'
- Alliance of Twelve from the Alias TV series
- Alliance (DC Comics), an organization of alien freedom fighters from the pages of DC Comics
- Anglo-Sino Alliance, powerful government and law-enforcement organization that controls a large sector of colonized "core planets" in the Firefly television series
- Earth Alliance (Babylon 5), fictional alliance of the countries of Earth in the television series Babylon 5
- Ferengi Alliance, fictional extraterrestrial race from the Star Trek universe
- Rebel Alliance, interstellar political resistance force formed in direct military opposition to the Galactic Empire in the fictional Star Wars universe
- The Alliance (The Office episode), an episode of the television series The Office
- The Alliance (professional wrestling), professional wrestling faction which ostensibly consisted of World Championship Wrestling and Extreme Championship Wrestling
- Alliance Films, motion picture distribution/production company, which serves Canada, the United Kingdom, and Spain.
Video games 
- The Alliance, a military, cultural, and economic alliance between various races in the Warcraft series of video games
- The Alliance of Order in Warhammer, an alliance of Humans, Elves and Dwarves to counter the Forces of Destruction
- Systems Alliance, the representative body of humanity in the Mass Effect series
- In Marvel: Ultimate Alliance, the eponymous Alliance refers to a coalition of heroes that normally work independently of one another, or in separate units.
- Airline alliance, an agreement between two or more airlines to cooperate on a substantial level. The three largest passenger alliances are the Star Alliance, SkyTeam and Oneworld.
- Burk, Kathleen and Melvyn Stokes (eds.): The United States and the European Alliance since 1945 (Oxford: Berg, 1999).
- Heuser, Beatrice, "Alliances Bedevilled by History: Franks, Germanics and Anglo-Saxons in the Cold War", in Luciano Tosi (ed): Europe, its Borders and the Others (Naples: Edizione Scientifiche Italiane, 2000), pp.313-349.
- Hunt, Peter: War, Peace, and Alliance in Demostenes' Athens (Cambridge University Press, 2010)
- O'Neill, Robert, Alliances and International Order (1988)
- Phillips, Charles and Alan Axelrod (ed), Encyclopedia of historical treaties and alliances. Vol. 1, From ancient times to World War I (Chicago & London: Fitzroy Dearborn, 2001)
- Strategies Alliances and Military Power: Changing Roles". With contributions by the Faculty and Staff of the Strategic Studies Institute at the United States Army War College, Carlislse Barracks, Pennsylvania, USA (Leyden: Sijthoff, 1977)
- Weitsman, Patricia A., Dangerous Alliances: Proponents of Peace, Weapons of War (Stanford, CA: Stanford University Press, 2004)