Social Security is the largest source of income for most elderly Americans today, but Social Security was never intended to be your only source of income when you retire. You will also need other savings, investments, pensions or retirement accounts to make sure you have enough money to live comfortably when you retire.
Saving and investing wisely are important not only for you and your family, but for the entire country. If you want to learn more about how and why to save, you should visit www.mymoney.gov, a federal government website dedicated to teaching all Americans the basics of financial management.
--from What Social Security Means To You, an SSA publication