FHA loans are insured by the gov't - and allows first time homebuyers to put down as little as 3% and a credit score as low as 580 (conventional loans require a credit score over 640, typically closer to 720). The gov't had multiple programs to encourage this demographic to buy homes, including tax breaks and grants.

Then you have subprime lending - very risky - and often with adjustable rates. This is where a lot of people got into trouble - and many people think they should have never been given loans in the first place.