You can start giving your child an allowance at any age, but age 7 is generally the best. This is the age when children really start to understand the concept of money and that it can help them get what they want by saving up for it. It's also a good way to help teach your child about responsibility. Children learn to be responsible for their own money, if they lose it or spend foolishly they have to deal with the consequences themselves. Children learn the value of money, and appreciate it more.
Children learn to work for what they want.
Children learn how and why to save money. Some quick cons for giving an allowance. Kids may still want parents to buy things for them. Kids will complain that their allowance isn't enough. Kids will say it takes too long to save the money for what they want to buy.