The World War I era centers on the years around 1914 to 1918. It includes the events before, during, and just after the war. This period involved many countries, especially in Europe.

Fighting took place in trenches, where soldiers lived and fought for long periods. New technologies such as tanks, airplanes, and chemical weapons were used. The war spread across Europe, the Middle East, and parts of Africa.

The conflict ended in 1918, followed by the Treaty of Versailles in 1919. Empires such as Austria-Hungary and the Ottoman Empire changed or ended. New countries formed from these changes.