What were the cause of World War I?

Good question, ww1 actually resulted from European countries having secret alliences the ones I can remember are that Germany was with Austria Hungary, and France was allied with Serbia. But war broke out when the Austrian Arch Duke was assassinated by a serbian nationalist and in response Austria went to war with Serbia inturn Germany declared war on Serbia and France declared war on Germany but Britain joined the war when Germany invaded the neutral country of Belgium.