cPro = Pro for Central
cPro is a lightweight version of Pro that is freely available to Central users. cPro does not allow local storage of projects. When using cPro, all of your projects reside in Central. cPro does will keep an internal copy of one project which allows you to work while you are disconnected from the Internet.
cPro is very handy when you can't connect to Central and when you would like to take advantage of the rich planning environment provided by a native desktop application.
You may upgrade to SharedPlan Pro which will enable you to save projects locally and enable other collaboration features.