There is always lots of talk about GPL and non GPL extensions in open source communities. Previously I never gave it to much thought until last week when it affected me very harshly.

GPL & non-GPL
For those of you who dont know what GPL is, it is the General Public License and it is the license Joomla and many other open source projects are released under.  The GPL states that any licensee  "is given permission to modify the work, as well as to copy and redistribute the work or any derivative version. The licensee is allowed to charge a fee for this service, or do this free of charge. This latter point distinguishes the GPL from software licenses that prohibit commercial redistribution. "

Generally speaking I have observed that most non-GPL extensions are encrypted. This means initially to install it you will have to first install a "Loader" to handle the reading and execution of the extension (more overhead). Additionally you can't see the source code to make modifications, learn from the code,  use the code to further advance the project, spurn a new project or self support for problems that arise.