Affordable housing
Most people work; they have a monthly income. To see if housing is affordable, people look at the amount of money that is spent on housing, in relation to the mothly income. When housing gets more expensive, people have to spend more of their income on it. Assuming that income doesn't increase, housing gets less affordable.  The Housing market sets the price for places to live. In many places, people who do not earn a lot of money, or who are in a difficult situation can ask the government for help.  They can then rent a place, where the state pays part or all of their rent. This is known as social or subsidized housing.