text:  So informal settlements are sometimes known as slums or deprived areas. There are many different terms, but essentially it's the neighborhoods of the cities. They're not officially registered. That's why they're called informal. And they often tend to have worse building materials. So they're not constructed according to the building codes. The buildings are very small and close together. Think of like favelas or shantytowns or many different names for these types of neighborhoods. And why are they in particular vulnerable to flooding?