Many students, when asked what FOSS is, immediately say it is software available for free (gratis). You are allowed to download it, install it, and copy it for no charge. This is true (kind of), but this is just the beginning of the story.
Gratis or libre?
The “Free” in FOSS doesn’t refer to no cost (gratis) – it refers to being free (libre). Free software means you have the freedom to do what you want with it. This includes downloading it, copying it, installing it, and using it as you want. But – perhaps confusingly – this freedom includes the freedom to sell FOSS for money!
To achieve this freedom, a critical FOSS concept is that the software’s source code must always be made available to users. This means users are always free to make changes to the software if they want. If they do make changes, they are usually required to make their source code available too. This way, everyone can benefit from their changes.
Why would people pay for FOSS?
If you are a large business with hundreds of computers, servers that must have a high uptime, and users who need support, you might find it useful to buy FOSS from a vendor who can offer the software plus installation, upgrades, documentation and end user support. A good example of this type of company is RedHat. They offer Redhat Enterprise Linux, plus the support large companies need. But, because Linux is FOSS, RedHat are also legally required to make RedHat Linux source code available for free download (indeed, you can get it from their site). So why do people pay RedHat? Because RedHat have a great deal of knowledge and experience of running RedHat Linux on many systems, so they are able to provide top quality support for their users. For a business – where wasted time is wasted money, this is critical.
So in summary, FOSS is a lot more than “something I can download for free”. An oft-repeated mantra is:
Free as in “freedom”, not “free lunch”