The Armistice of 1918 marked the end of World War I, with an armistice signed by the Allies and the Germans. It was not intended to be a permanent peace deal, and it was redrafted at the Treaty of Versailles, to which Germany was not invited.
November 11th became a holiday in many Allied countries, including the United States. After World War II and the Korean War the name was changed from "Armistice Day" to "Veterans Day" to honor all veterans, not just World War I veterans.
Source: https://learning.blogs.nytimes.com/2011/11/11/nov-11-1918-world-war-i-ends/
