I found this on the internet: “Some firmware images are free and open-source, and some of them are non-free, which means that you would need to add the non-free and contrib components to your APT sources.”
Is it legal to install non free firmware when I want to install debian?
Hi, well, technically I can see hot the “non-free” bit might sound a little worrying. However (!) non-free in this context doesn’t mean necessarily “paid for”, but rather that it comes with “strings attached”. These strings would typically be detailed in the terms and conditions provided and might be something like; you agree not to try to reverse engineer the code, modify it, put your name on it and sell it etc etc …".
So the answer literally would be; “it depends on the terms and conditions / license that comes with the firmware in question”, but typically, I would not expect Debian to include any software that would be illegal to install. So “non-free” in this context typically means “you’re not free to do whatever you want with it”, rather than “you need to pay for it”.
(Caveat; some software I guess may be subject to export licenses and sanctions etc, so if you’re installing in certain countries then I guess there may be an issue … but for the countries I have in mind, it still may not be an issue … 
)
… there is always a trade-off between being able to read and track the terms and conditions for every bit of software you use (which IMHO would be quite an ask) , and trusting your supplier not to lure you into installing something you shouldn’t.
Edit: it would seem there is a technical definition of what goes into “non-free”, which is software whose license does not comply with Debian’s definition of “free software”. (Debian Social Contract)
Debian has for a long time supplied non-free firmware images and images with non-free firmware they are going to change to supplying non-free firmware images as official.
Mmm, interesting. However, just to clarify for anyone a little worried about the wording or expression “non-free”. In context, this typically refers to “device drivers”, which are essentially a layer between your computer and potentially ‘exotic’ hardware that may provide non-standard features or features not supported by device drivers that are included within the Linux kernel. In the same way, when you buy a TV it will likely include some “non-free” software, but this is included within or covered by the cost of buying the hardware. When you buy a car, it will likely include … etc. i.e. non-free in this context just means the hardware manufacturer wants to hang on to the rights to it’s code, rather than making it open source. (i.e. it doesn’t mean it is wanting to explicitly charge for it, it’s just ‘a feature’ that allows them to sell more devices)
That said it is an interesting move by Debian, one of the larger targets of criticism in this area has been NVIDIA. Many people rely on NVIDIA graphics drivers, but they have long been “non-free”. However I read that as of release 15, they will be Open Sourcing their driver under an MIT license.
So, a bit of a contrast, distro’s potentially reversing decisions over including non-free software as the same time as leading non-free software vendors are making their software free … (!)
There are various things involved here.