The freedom to run the program means the freedom for any kind of person or organization to use it on any kind of computer system, for any kind of overall job and purpose, without being required to communicate about it with the developer or any other specific entity. In this freedom, it is the user's purpose that matters, not the developer's purpose; you as a user are free to run the program for your purposes, and if you distribute it to someone else, she is then free to run it for her purposes, but you are not entitled to impose your purposes on her.
This could be the most high-end free software ever: it's the very tool used to render the images you see in Pixar's movies. That's because RenderMan was developed by Pixar in-house for that purpose, but became free for non-commercial use. It's not going to do you much good without other software such as Autodesk's Maya for creating 3D models. But budding artists and filmmakers will want to take note. You'll need a 64-bit system to run it.
The Linux kernel, started by Linus Torvalds, was released as freely modifiable source code in 1991. The first licence was a proprietary software licence. However, with version 0.12 in February 1992, he relicensed the project under the GNU General Public License. Much like Unix, Torvalds' kernel attracted the attention of volunteer programmers. FreeBSD and NetBSD (both derived from 386BSD) were released as free software when the USL v. BSDi lawsuit was settled out of court in 1993. OpenBSD forked from NetBSD in 1995. Also in 1995, The Apache HTTP Server, commonly referred to as Apache, was released under the Apache License 1.0.
Something to always watch for: crapware installers. To make ends meet, many creators of otherwise great free software, or the services that offer the programs for download, bundle in things you don't want. Worse, the installation routine obfuscates the steps, so you provide the unwanted program tacit permission to be installed. For more about how to spot and avoid this problem, see How to Clean Crapware From a New PC, and check out the Uninstaller section of this very free software collection.
GIMP has a very different interface from Photoshop, and some people scratch their heads over its workflow. But generally speaking, GIMP is a lot simpler to use. It’s also free to download, and the software is regularly updated. GIMP has come along way since its clunky inception, and more and more Photoshop users are making the switch, or even cutting their teeth with this zero-cost alternative.
Many people new to free software find themselves confused because the word "free" in the term "free software" is not used the way they expect. To them free means "at no cost". An English dictionary lists almost twenty different meanings for "free". Only one of them is "at no cost". The rest refer to liberty and lack of constraint. When we speak of Free Software, we mean freedom, not price.
The best thing about some of these companies is that you don't have to "Like" them on Facebook, send messages on Twitter, or complete surveys. With the companies I've listed first, simply sign in, input your mailing information, and wait for the free sample to show up in your mail). It will take less than 15 minutes sign up and up to six weeks for samples to arrive.