Windows Azure platform pricing options range from "pay as you go" to commitment. If you want to try Azure with no financial commitment, sign up for Introductory Special offer, which allows you to try a small amount of Azure resources at no charge. When you sign up, you'll be asked for a credit card but your card willn't be billed as long as you stay within the no-charge amount included in the offer.
If you don't want to make long-term financial commitment, select Standard consumption offers and simply pay for what you use. And, for a 6-month commitment, select Commitment offers, which provide a significantly discounted price in return for a six-month commitment to pay a monthly base fee.
Click the links below to see a full description of what's included in each offer: