Free software, as defined by the Free Software Foundation, and they can be used, copied, studied, modified and redistributed for free etc. Free software is sometimes referred to by other names such as libre software. The opposite of free software is not commercial, but rather proprietary software.

Most free software is distributed gratis or offline for minimal cost of distribution, but this is not required, and people are free to sell copies for any money price. Richard Stallman (founder of the Free Software Movement) coined the phrase, free as in, and is not as in free beer to help people understand the difference between libre software and free software.