FDIC Insured.....

[nokia1566]

I was reading something on ING where it says that my money is FDIC insured up to $100,000. I am pretty much clueless as to what this means so if someone could elaborate it would be helpful... I guess what I am wondering is, what am I risking by having $200,000 in the account? What are possible threats to my money? What could cause my money to basically be lost and then only get $100,000 back (from the FDIC)?

Thanks