"The Triple Entente (from French entente [ɑ̃tɑ̃t] "friendship, understanding, agreement") was the understanding linking the Russian Empire, the French Third Republic, and the United Kingdom of Great Britain and Ireland after the signing of the Anglo-Russian Entente on 31 August 1907. The understanding between the three powers, supplemented by agreements with Japan and Portugal, constituted a powerful counterweight to the Triple Alliance of Germany, Austria-Hungary and the Kingdom of Italy, though Italy did not side with Germany and Austria during World War I and joined the Entente Powers instead, in the 1915 Treaty of London.
Historians continue to debate the importance of the alliance system in igniting the Great War. At the start of World War I in 1914, all three Triple Entente members entered it as Allies of World War I against the Central Powers, Germany and Austria-Hungary. However, it is important to note that the Triple Entente, in contrast to the Triple Alliance or the Franco-Russian Alliance, was not an alliance of mutual defence and Britain therefore felt free to make its own foreign policy decisions in the July crisis in 1914."