Use Bind when
- You need to bind a call to a free function, and some or all of its arguments
- You need to bind a call to a member function, and some or all of its arguments
- You need to compose nested function objects
The existence of a generalized binder is a tremendously useful tool when it comes to writing terse, coherent code. It reduces the number of small function objects created for adapting functions/function objects, and combinations of functions. Although the Standard Library already offers a small part of the functionality found in Boost.Bind, there are significant improvements that make Boost.Bind the better choice in most places. In addition to the simplification of existing features, Bind also offers powerful functional composition features, which provide the programmer with great power without negative effects on maintenance. If you've taken the time to learn about bind1st, bind2nd, ptr_fun, mem_fun_ref, and so forth, you'll have little or no trouble transitioning to Boost.Bind. If you've yet to start using the current binder offerings from the C++ Standard Library, I strongly suggest that you start by using Bind, because it is both easier to learn and more powerful.
I know many programmers who have yet to experience the wonders of binders in general, and function composition in particular. If you used to be one of them, I'm hoping that this chapter has managed to convey some of the tremendous power that is brought forth by the concept as such. Moreover, think about the implications this type of function, declared and defined at the call site, will have on maintenance. It's going to be a breeze compared to the dispersion of code that can easily be caused by small, innocent-looking  function objects that are scattered around the classes merely to provide the correct signature and perform a trivial task.
The Boost.Bind library is created and maintained by Peter Dimov, who has, besides making it such a complete facility for binding and function composition, also managed to make it work cleanly for most compilers.