Freeware, also called free software1, refers to any computer program that does not require the user to pay for it (although voluntary donations can be accepted). It does not, however, imply the lack of a license or the availability of source code; indeed, such software can often have a restrictive licenses, limiting or forbidding commercial use, redistribution and modification of the program, use on more than a certain number of computers, and so on. Freeware programs with such restrictions often have accompanying commercial versions that relax or remove those restrictions, but require a license to be bought.
Freeware is sometimes erroneously used to refer to trial versions of shareware, which are time- or functionality-limited versions of commercial software. In the latter case this is sometimes justified, as the line between a functionally limited trial version of a shareware program and a freeware program with a more fully-featured, commercial version can often be blurry.
1 The Free Software Foundation insists that freeware be distinguished from free software (also known as software libre), where "free" refers to the lack of restrictions on using and modifying the software ("free as in speech"), rather than just the lack of monetary cost ("free as in beer").