Oh boy this is a huge topic. I'll give a quick answer. Africa was isolated from Europe for a long time. During that time Africa (with the exception of East Africa and North Africa) developed little technology. The Europeans set up colonies in Africa to get diamonds, ivory, spices, gold, etc. Finally the Europeans decided to leave, but before they did they set up "countries". No thought was given to the demographics of these countries. Different tribes that had historically never gotten along were no within the same border. This lead to civil wars and genocides with the most famous being Rwanda. Also the governments were/are corrupt so most of the aid money stays with the leadership. Thus poverty.
