It's one of the biggest assets, if not the biggest asset, for millions of Americans in or near retirement. Despite a global financial crisis, it has kept all its value.

But we have little practical knowledge of this asset -- assuming we even think about how to get the most out of it.

I am taking about Social Security retirement benefits, which by all rights should be a major component of any retirement income plan.

Consider: The average monthly Social Security retirement benefit, after a 5.8 percent cost-of-living increase, will be about $1,153 in 2009. To receive that much inflation-adjusted income for life, a 65-year-old man would have to pay an insurance company a lump-sum premium of about $204,000 for an immediate annuity, and a 65-year-old woman about $225,000, based on the lowest quotes I found from highly rated companies.

Is your IRA or 401(k) worth that much? In addition, Social Security offers attractive spousal and survivor benefits.

Clearly, we should pay attention to the ins and outs of Social Security. The decision of when best to start collecting benefits -- as early as age 62 for unreduced benefit to as late as age 70 for enhanced benefits, or anywhere in between -- can hinge on many factors.

Aside from any immediate need for money, these factors include how long you expect to live, your tax bracket, whether you're still working, and whether you are single or married.

"Social Security-related decisions can be complex and there can be trade-offs," said Carolyn Clancy, an executive from Fidelity Investments. A recent online survey commissioned by Fidelity shows many Americans lack the basic knowledge to understand these trade-offs and make informed decisions. Continued...