At some point, the Social Security system touches the lives of almost all Americans. Some 155 million workers pay taxes to finance the benefits program; another 54 million Americans currently receive benefits. The beneficiaries are not only retired people but also those who have been disabled by injury or illness, the survivors of workers who have died and dependents of beneficiaries.

To handle all those needs, the system must be fairly complex; the government wants you to understand how it works and how you can obtain the benefits that you are owed. Social Security: Understanding the Benefits (PDF), the Social Security Administration's free 22-page publication, provides a nuts-and-bolts explanation of everything from eligibility rules to how payouts are calculated.