The ellipsis is an oddity of C++. As said by sean, it can be used for having a variable number of parameters to a function (called variadic parameters). Also, it can be used (as in the try catch example above) to accept any parameter (as in catching any and all exceptions). For the most part, this keyword should be avoided as it is usually bad design and requires care when using it. It does find more usefulness in certain template meta-programming techniques or to provide a default overload for a function. But, basically, I cannot recall a single place where I have used it in the past, and that's a good thing.