I often talk about supporting free software. But what is free software? People often (and incorrectly) believe that when I say free, I mean free as in 'free beer'. That simply isn't true - when I say 'free software', I mean free as in freedom.
Software that is free, is software that respects the users' freedom. Specifically, to be considered free software, a piece of software must respect the 'four essential freedoms', as defined by the Free Software Foundation (FSF). Those freedoms are as follows: (quoted from the GNU project's website)
For software to be able to respect these freedoms, it must be published under a copyright license that grants users these freedoms. The most influential free-as-in-freedom copyright license is the GNU General Public Licence (The GNU GPL), which not only grants users these freedoms, but ensures that all derivative works that use the GPL'ed code must also grant users these freedoms. Free-as-in-freedom copyright licences that require derivative works to be published under compatible licenses, are known as copyleft licenses.
Programs that are published under licenses that don't grant users these freedoms are known as proprietary licenses. Software from Micro$oft, Apple, Adobe, Google, and many other companies is proprietary, and should be avoided, as that software takes advantage of users, invades their privacy, and normalizes proprietary software. Free-as-in-freedom software needs to be the norm in a world that is so heavily digitized. Digital freedom does not exist without free software.
For a more detailed explanation, visit this page on the GNU project's website.
Free software is everywhere. Basically every site you visit is powered by a free-as-in-freedom webserver (usually Apache or NginX), which is almost definitely installed on a machine that is running a free operating system (usually GNU/Linux or a variant of BSD). Even proprietary software you use is likely compiled with free tools, and likely contains free code.
In this age of digitization, it is literally almost certain that at least some of your appliances are running free software. GNU/Linux is used widely for embedded applications, and it is 100% possible, even likely, that the Linux kernel is running the control system on your microwave oven. For the tiny amount of appreciation it gets, our world - from microwaves to computers to airplanes - would grind to a halt without free software.
Yes. If you are interested in switching to free software to protect yourself and the movement, visit this lovely wiki of free software projects, or this list of GNU software.