How did alliances contribute to the start of the war World War 1?

Alliances significantly contributed to the outbreak of World War I by creating a web of obligations that drew multiple nations into conflict. The assassination of Archduke Franz Ferdinand of Austria-Hungary prompted Austria-Hungary to declare war on Serbia, which in turn activated Russia's alliance with Serbia. This escalated tensions as Germany, allied with Austria-Hungary, declared war on Russia, leading to further declarations of war among the interconnected alliances of France, Britain, and others. The complex alliance system transformed a regional conflict into a full-scale global war.