Buying a home is the embodiment of the American dream. However, that wasn’t always the case: In fact, before the 1930s, only four in 10 American families owned their own home. That’s because very few people had enough cash to buy a home in one lump sum. And until the 1930s, there was no such thing as a bank loan specifically designed to purchase a home, something we now know as a mortgage.

In simple terms, a mortgage is a loan in which your house functions as the collateral. The bank or mortgage lender loans you a large chunk of money (typically 80 percent of the price of the home), which you must pay back -- with interest -- over a set period of time. If you fail to pay back the loan, the lender can take your home through a legal process known as foreclosure.

For decades, the only type of mortgage available was a fixed-interest loan repaid over 30 years. It offers the stability of regular -- and relatively low -- monthly payments. In the 1980s came adjustable rate mortgages (ARMs), loans with an even lower initial interest rate that adjusts or “resets” every year for the life of the mortgage. At the peak of the recent housing boom, when lenders were trying to squeeze even unqualified borrowers into a mortgage, they began offering “creative” ARMs with shorter reset periods, tantalizingly low “teaser” rates and no limits on rate increases.