The RooFit packages provide a toolkit for modeling the expected distribution of events in a physics analysis. Models can be used to perform likelihood fits, produce plots, and generate "toy Monte Carlo" samples for various studies. The RooFit tools are integrated with the object-oriented and interactive ROOT graphical environment.
RooFit has been developed for the BaBar collaboration, a high energy physics experiment at the Stanford Linear Accelerator Center, and is primarily targeted to the high-energy physicists using the ROOT analysis environment, but the general nature of the package make it suitable for adoption in different disciplines as well.
For a quick overview of what RooFit can do, have a look at the PHYSTAT2005
write-up on RooFit (here), or download the Users Manual (here),
or have a look at our (now slightly outdated) 10 page RooFit web slide show.