Linus Torvaldis is famous for inventing Linux, a version of Unix which would run on Intel *86 PCs. To be fair, what Linus did was put the last vital piece into place, the "kernel" of the operating system, which handles process control, networking, and peripheral and file system access.
The development of Linux is one of the most prominent examples of free and open source software collaboration; typically all the underlying source code can be used, freely modified and redistributed, both commercially and non-commercially, by anyone under licenses such as the GNU General Public License.
Linux itself costs nothing. One is allowed to charge a reasonable cost for the medium of distribution, and charge for supporting Linux, but the actual operating system is free.
The popularity of Linux on standard desktop computers and laptops has been increasing over the years, even though its performance on the desktop has been criticized.
In 2007, Con Kolivas accused the Linux community of favoring performance on servers. He quit Linux kernel development because he was frustrated with this lack of focus on the desktop, and then gave a "tell all" interview on the topic. Since then a significant amount of development has been undertaken in an effort to improve the desktop experience.