Market failures can really mess up the regular supply and demand model. Here are some ways they challenge these ideas:

1. Externalities:

   • This happens when a third party is affected by a deal—like pollution from a factory. The real cost of this pollution isn't included in the market price. Because of this, we often use too much of something or not enough.

2. Public Goods:

   • Things like national defense or street lighting are important but aren’t sold in regular markets. This can lead to not having enough of them because people don’t want to pay for something they can use for free.

3. Imperfect Information:

   • When buyers don’t have all the information—like when buying used cars—they can't make smart choices. This can throw off supply and demand.

These problems show how real-life situations can change economic ideas, making things a lot more interesting!