Gaza and Haiti are on the brink of famine, experts say. Here's what that means.

A new report warns that famine is imminent in Gaza as fighting between Israel and Hamas continues. Aid groups say that 1.4 million people in Haiti are on the verge of famine. Famine occurs when households and entire regions or countries reach a catastrophic level of hunger and lack of access to food. Famine is the highest, most dire level of a five-phase scale put in place in 2004 by an international coalition of government and aid groups that monitor the severity of hunger in the world. Children younger than 5, pregnant women, the elderly and those underlying health conditions are most at risk.