Here's a summary of the crisis in Somalia as of now. An "internally displaced person" is someone who has been forced to flee their home due to the threat of violence to themselves or as the result of a natural disaster. In the case of Somalia, the people are displaced because of the violence from the war there. Remember, these people haven't just moved away from a previous place of residence, they have been violently coerced, one way or another, from their homes and are now homeless. They can only survive on sustenance provided by aid organizations and the kindness of anyone else willing to help them.