Belgium is one of the 12 countries that use the Euro as its national currency (along with Germany, Greece, Spain, France, Ireland, Italy, Luxembourg, the Netherlands, Austria, Portugal and Finland).

The Euro is broken up into 100 cents.

Coins of 1, 2, 5, 10, 20 and 50 cents are available as well as coins of 1 and 2 Euros. Euro Bills range from 5, 10, 20, 50, 100, 500 to 1000.

Money can be exchanged at most banks and foreign exchange offices, as well as Traveler's Cheques, but these are less and less popular.

 ***Recent experience indicates that many banks and post offices no longer offer exchange for US dollars. In September 2006, it was difficult for travelers to find any facility outside airport that would change dollars.

For each 'amount' you have a different 'card' :

SMALL amounts (a few cents or a few euros) : the PROTON card.

This is a function the Belgians have on their bank pass. It's money pre-loaded on the card. You can use it in a variety of (vending) machines and dispensers, phone booths, in shops, at parking lots, ... In the Netherlands this card is known as 'chip-knip', but both systems are not interchangeable. As a foreign visitor you don't have this 'proton' function unless you open a Belgian bank account.

For INTERMEDIATE amounts (from 10 to hundreds of Euros) : the MAESTRO function on you bank card.

This is very popular, and every self respecting Belgian shop (except those dealing with very small amonts like news paper stands) has a Maestro terminal. Don't hesitate to use it of you have the logo on your card. Don't mix up with 'mastercard', that's something else.

For LARGE amounts (over 50 Euro for instance) : a CREDIT CARD.

Of course you can also use the Maestro function. Don't try and use your credit card for small amounts in Belgium. Most gas stations are unstaffed even during the day and you'll need a MAESTRO card. Credit cards only work in some rare unstaffed stations, and in staffed stations. VISA and EUROCARD are more widely accepted than others.

ATM machines (called Bancontact...don't ever ask "where is the nearest ATM?") are widely available in all major cities and touristic places.  You can get cash with your MAESTRO function or with a credit card. But since Maestro payment in shops is so popular, try directly paying with the card in shops rather than first get cash. ATM's are to be found in banks (be it on the outside or inside), but NOT in gas stations, restaurants or other popular venues. In these places, pay directly with your MAESTRO. ATM's can be used to recharge prepaid phone cards, proton cards, and some machines inside banks have a wealth of other functionalities, usually only on offer to account holders from the bank the ATM is found at.

ATM's distribute 20 and 50 Eurp bills and often instructions are available in 4 different languages. 

Personal cheques belong to the ice age in Belgium. For money transfers between people and companies, Belgians use bank transfers.