Interest rate swaps are agreements where two parties exchange fixed rate debt for floating rate debt. These swaps have been around since the 1980s and involve multiple cash flows over time. In addition to plain-vanilla swaps, there are other types like caps, collars, floors, and swaptions. The value of these swaps is determined based on interest rates. Caps, collars, and floors, as well as swaptions, are also discussed in the article.