The government gives you the option of taking a reduced pension early (as early as 62) or an enhanced pension later (as late as age 70) - smaller payments for a longer time or larger payments for a shorter time. On average it works out the same for the government. But for individuals, the enhanced benefit is usually the better deal because it provides a higher guaranteed lifetime inflation-adjusted income (additional 8% for every year you delay). This provides some protection against outliving your money.
A few individuals are able to take a Social Security spousal or widow(er) pension during part or all of the period when they are delaying their own benefit.
Regardless of whether or not you are already receiving a benefit, you MUST apply for your own Social Security pension by age 70. The government will NOT automatically send you your pension, or switch from your dependent/survivor pension to your own higher pension.
If you did not apply for your own benefit when you turned 70, you may apply for retroactive benefits for up to 6 months when you do apply.