Specific: Smart goals are specific enough to move a person into action.
Example: Save enough money to get a refrigerator (as opposed to, simply, "Save some money.")

Measurable: You need to know when you have achieved your goal, or how close you are.
Example: A refrigerator costs $600, and you have $300 already saved.

Goals which aren't measurable, like "I'd just like to have more money," are much harder to achieve. What's more, there's no way to tell when you've gotten there!

Attainable: The steps toward reaching your goal need to be reasonable and possible.
Example: I will put aside enough each week to reach my goal within one year.

Relevant: The goal needs to make sense. You don't want to work toward a goal that doesn't fit your needs.
Example: You don't need to save money for 18 pairs of shoes.

Time-related: It's important to set a definite target date.
Example: The repairman says my refrigerator will last another year, but no more. My goal is to save enough to buy a new fridge in ten month's time.