The article in that link explains better than I can, but in short:
Restricted Application: you file only for benefits that aren't your regular benefits.
People used the "restricted application" to claim benefits based on their spouse's social security instead of their own, so long as they and their spouse had reached "Full Retirement Age".* They would let their own Social Security benefit grow until it got as high as possible (age 70) and then switch to those. In the meantime, they were getting money every month that was the equivalent of half of their spouse's monthly payment.
Also, once you take spousal benefits, that's what you're committing to. You can't switch to your "own" benefits at age 70 any more.
File and Suspend: the other half of this strategy is (was?) to "File and Suspend". Because the above-mentioned spouse could only claim their "spousal benefits" if the other one had filed for themselves, THAT spouse would file... but then defer getting any payments for themselves until age 70, when the payments would be higher.
This went away for anyone born after 1953. Once you start your benefits you just start them. If you hold off on starting til age 70, that means your spouse can't get "spousal benefits" til then either.
File and Suspend is still available, if it applies to you, until April 29, 2016.
(Getting rid of File and Suspend is annoying but not, in my opinion, that huge of a deal.)
By the way, both of these strategies will continue to be to available to people born in 1953 or before
This blog post by my fave blogger, Michael Kitces, has a good chart to help you figure out which timeline applies to you. It's especially handy because it also covers benefits for divorced spouses and benefits for dependent or disabled kids of people who are of an age to collect Social Security benefits.
*Full Retirement Age is often called "FRA" by the Social Security Administration and it's a specific age that they designate (usually age 66 or 67, depending on how young you are.). It has nothing to do with the age at which you stopped work.
I'm busy working on my blog posts. Watch this space!