Why do some countries face starvation when others don't?

Any given country does not necessarily have to produce all of its own food, since it is possible to import food from other countries which produce more food than they eat. However, in order to import food it takes money, and that money is obtained by selling something. A nation that has a healthy economy, therefore, does not face starvation. If they have any substantial exports, they can use the resulting income to buy food, even if farming conditions in that country do not allow enough food to be grown to feed the local population. Thus, Libya grows very little food, but it exports oil, so the Libyans do not starve. But Somalia grows little food and also has no real exports, so it does starve.