FLOSS & MARKET
The ideological basis of free software is freedom, against prohibitions. The GNU GPL licence doesn't foresee any commercial prohibitions.
Free distribution means also free marketing (but, obviously, at the same time, others can commercialize on it as well as giving it out for free).
A free or open-software, does not necessarily coincide with not-paid activities. The software market is widely supported by enterprises that commercialize free/opensource software and the services connected to it.
Any user can install a GNU/Linux system or an Apache server on his computer by freely downloading the kernel and all the components he considers interesting, but there are enterprises - linked to the free software/opensource such as Debian and RedHat - which put together and test the software components and provide personalised releases. They charge for their expenses and services.
Such enterprises often devote a certain amount of their profits to further improve and develop the open-source software.
Yet there are also “traditional” companies that build part of their business on OS software and therefore support its growth. Linus Torvalds, for example, works full time today to coordinate the group of programmers who develop the kernel Linux on the behalf of OSDL (Open Source Development Lab), a project funded by Computer Associates, Fujitsu, Hitachi, Hewlett-Packard, IBM, Intel, and NEC.