And your rights to modify the source code may be restricted. With shareware, the traditional model is somewhat reversed. The software is distributed for free, and may even be passed on to others. Users of the shareware product are honor-bound to pay the developer's registration fee, whatever it may be. A variant on this licensing scheme, termed crippleware, will not function fully until the registration fee is paid.
Freeware is shareware with no registration fee.
The source code is typically not included with any of these. Free Software Free software, on the other hand, is all about access to the source code. Under the free software licensing model, it is your right to use the software, modify it, and redistribute it in any way you like. It's even okay for you to charge for your distribution. However, these broad rights are conditioned upon your commitment to provide similar access to your modifications and to never narrow the licensing rights as a condition of distribution.