Price Ceiling

A price ceiling establishes a maximum price for a product - sellers can’t go over this price.

An example of this is rent control in New York City - prices can’t go higher than the agreed-upon price. However, landlords may not want to rent these out at that price - so there’s a shortage.

Price Floor

A price floor establishes a minimum price for a product - sellers must go over this price.

An example of this is military supplies.

Rationing

Rationing is limiting demand by allocating resources through factors other than price. This often leads to a black market - because quantity isn’t being adjusted based on price, and shortages are more likely to happen.

Excise Taxes

It just puts a tax or a fee on an action - purchasing a good or service.

The impact of these taxes is just a triangle - but again. It’s the difference between the original equilibrium price and the one after tax, times the difference between quantities, divided by two. You can decide when you want to divide the two.