How did the tangled alliances create a world war?

The tangled alliances in Europe before World War I created a web of commitments that escalated regional conflicts into a global war. When Austria-Hungary declared war on Serbia in response to the assassination of Archduke Franz Ferdinand, Russia mobilized to support Serbia, prompting Germany to declare war on Russia. This chain reaction drew in other nations due to existing treaties and alliances, such as France and Britain, ultimately transforming a localized conflict into a full-scale world war. The interlocking obligations of various countries meant that a single conflict could quickly engulf multiple nations, leading to widespread warfare.