Before going into more details in the presentation, it could be useful to give some definitions of terms and software mentionned in that Howto.
A free software (or Open Source software) is a software distributed with its source code, allowing its study, its transmission, its adaptation.
Depending on the licenses used for its development, the constraints for users of such a software are various. The most open licences (like the BSD one) allow code appropriation by third parties, including the reselling of the resulting software (with or without modification) in commercial products, without any problem, and without owing something else to the originators than the mention of their copyright. Other licences (like the GNU Public Licence or GPL) force all modified GPL softwares to be free GPL softwares themselves ; this doesn't allow the use of such programs in a commercial one. Many other licences exist, more or less open: the Artistic Licence (perl), the NPL one (mozilla), the QPL one (Qt) ...