How did the complex web of european alliances contribute to the outbreak of world war i?

The complex web of european alliances contributed to the outbreak of world war i by forcing other countries into the war. To elaborate if "A" was friends with "B" then b got into a fight was "C" a would of course help his friend b, But b was friends with "D" and this lead to a never ending chain which caused all of Europe to be engulfed in war.

Ifeel like this is a very good quesyion