In financial mathematics, the Hull-White model is a model of future interest rates. In its most generic formulation, it belongs to the class of no-arbitrage models that are able to fit today’s term structure of interest rates. It is relatively straightforward to translate the mathematical description of the evolution of future interest rates onto a tree or lattice and so interest rate derivatives such as Bermudan Swaptions can be valued in the model. The first Hull-White model was described by John C. Hull and Alan White in 1990. The model is still popular in the market today (from Wiki).