Why Do We Put Money into "Piggy" Banks?

Most people are probably more concerned with how much money is saved in their piggy bank rather than wondering why exactly we save our spare coins in pig-shaped containers. But how did those containers get that shape?

Majapahit terracotta piggy bank, 14th-15th century
 Trowulan, East Java.
(Collection ofNational Museum of Indonesia,Jakarta)

Containers for storing coins, known as moneyboxes or coin banks, have been used for centuries. To encourage saving, a small slit was placed on the top of these so that coins could enter but not exit. Because the only way to get the coins out was by breaking the container, they were mostly made of cheap materials. Eventually, these simple containers evolved into piggy banks.

Early piggy banks are hardly ever found—they were shattered in order to retrieve the saved coins—which has made it difficult to study their beginnings. Still, a couple of theories exist regarding the origins of the piggy bank.

The most common legend of how piggy banks were created dates back to 15th century Europe, where a type of clay called pygg was used to make plates, bottles, and vessels. When people threw their spare coins into these types of pygg containers, they started to call them pygg banks. Eventually, through a misinterpretation of the word pygg as pig, potters began to construct moneyboxes into the shape of pigs. As a result, the piggy bank was invented.

More at Mental Floss and Wikipedia, and at Straight Dope, which adds this re the bank part of piggy banks:

OK, after that, "bank" must be simple. Not so fast. Bank originally meant "bench"; you can probably see the connection between the words. Money lenders in Northern Italy once did business in open areas, or big open rooms, with each lender working from his own bench or table. If he went "broke," the piece of furniture was literally broken to signify that he wasn't in business anymore.