Wikipedia - the Free Encyclopedia defines shareware as:

Shareware: is a marketing method for software, whereby a trial version is distributed without payment ahead of time as is common for proprietary software . Typically shareware software is obtained free of charge by downloading, thus allowing one to try out the program ahead of time. Shareware is also known as try before you buy, demoware, trialware and many other names. A shareware program is accompanied by a request for payment, and often payment is required per the terms of the license past a set period of time. The term shareware was coined by Bob Wallace to describe his word processor PC-Write in the mid- 1980s .

Wikipedia - the Free Encyclopedia defines freeware as:

Freeware: is computer software which is made available gratis/free of charge. Typically freeware is proprietary; distributed without source code. It usually carries a license that permits redistribution but may have other restrictions, such as limitations on its commercial use. For example, a license might allow the software to be freely copied, but not sold, or might forbid use by government agencies or armed forces.

The term was coined by Andrew Fluegelman when he wanted to distribute a communications program named PC-Talk that he had created but for which he did not wish to use traditional methods of distribution because of their cost. Previously, he held a trademark on the term "freeware" but this trademark has since been abandoned. He actually distributed PC-Talk via what is now referred to as shareware.

Commercial vendors often release freeware as a loss leader to attract customers to other services or products available for a fee. Others release freeware because other methods of distribution are unlikely to make a profit or because the software is outdated and is no longer worth selling.

Wikipedia - the Free Encyclopedia defines freeware as:

Trialware: In proprietary software (and some other commercial products), a trial version or trial or piece of trialware is a (usually gratis and FRS) version of a product that only works for a limited period of time (and sometimes has reduced functionality). A trial version of a software package (or piece of trialware) is often produced by a software publisher to help users get a feel for it before deciding whether to buy the full version. See the more general term, shareware.