Besides the moral and philosophical reasons for preferring free software, free software enjoys many practical advantages in its design, development, deployment, support, maintenance and reuse. Most of these benefits are already recognised and used by the free software community. These, and the resulting quality benefit, are now becoming very important for the spread of free software into the nonspecialist and business world. In this talk I shall describe these benefits and explain how they flow from the freedom of the software. I'll then examine what kinds of freedoms are necessary for these advantages to operate, and what the effects of various common restrictions are on them. Finally, I shall present a set of loose criteria which can be applied to a particular piece of software to see if it is sufficiently free to obtain these practical benefits (if not necessarily the moral ones).

Dr Ian Jackson has been involved in the free software community since 1992. He once maintained the Linux FAQ, and has been involved with many other Linux and free software projects. Ian has been particularly heavily involved with the Debian Project; he wrote the package installer `dpkg', and is currently the project leader. Ian's PhD was with the Cambridge University Computer Laboratory Security Group, on confidentiality of location; previously, Ian studied Engineering and Information Sciences at Churchill College, Cambridge. As a day job, Ian works as a cryptographer for nCipher, a Cambridge-based company. In his earlier years, Ian lived in a wide variety of places, including three years in Hengelo (in Overijssel, in the Netherlands).