I think that the answer you are looking for is $250,000. Of course, this does not mean that you get $100,000 back if your bank goes broke and you only had $250,000 in your account. What it means is that the FDIC will only insure the first $250,000 in any given bank account. As the FDIC's website says,
The standard deposit insurance amount is $250,000 per depositor, per insured bank, for each account ownership category.
The FDIC was set up so that people could deposit money in banks without having to fear that their deposits would be lost in the event of a bank failure. To that end, the FDIC guarantees that people will get their deposits back so long as those deposits do not exceed $250,000.