Why did the triple alliance develop

Triple Alliance, secret agreement between Germany, Austria-Hungary, and Italy formed in May 1882 and renewed periodically until World War I. Germany and Austria-Hungary had been closely allied since 1879.

The triple alliance was made up of a signed treaty between Italy, Germany, and Austria-Hungary and they opposed the triple entente which was composed of France, Britain and Russia. Each member promised mutual support in the event of an attack by another greater power.