Shareware distribution gives users a chance to try software before actually buying it.
If you try a Shareware program and continue using it, you are required to register it. Shareware is a distribution method, not a type of software. You should find software that suits your needs and pocketbook, whether it's commercial or shareware. The Shareware system makes finding this software easier, because you can 'try before you buy'. Usually due to low overhead, shareware prices are usually also low.