A better question is why are hard drives still being assigned drive letters? Multiple "roots" in the file system hierarchy is just plain stupid. You need to special case your path navigation commands for for drive letters. (E.g. cd v/s cd /d). etc.
The best place to do this is in the Disk Management app. The easiest way to access it is via the Win+X menu.
\\machine\c\your_folders \\machine\d\yet_more_folders
D: # changes to D: Drive
cd Videos # enter the Videos directory
cd "C:\Program Files\ffmpeg\bin"
At this point the prompt will still say D:\Videos>
and you can type "C:ffmpeg my-movie.avi" and Windows will execute ffmpeg from the "current directory" of the C: drive, but process the file D:\Videos\my-movie.avi .
I wonder what would happen if you called it A or B?
Having fixed letters is a bit antiquated, but drives as separate entities seems to match the real world quite well.
It is not part of the partition. It is just an arbitrary path that is mapped to your USB stick. You can choose where you want it to be mapped depending on your needs and what you are trying to do. There are conventions about where most Linux distributions will map removable media (/mnt or /media), but conventions do not have to be followed if you do not want to.
The "one filesystem" design of Unix / Linux is all about abstraction. Anything that follows file-like conventions can be mapped into the filesystem. For example, on Linux there is a virtual filesystem under /proc.
"/proc is very special in that it is also a virtual filesystem. It's sometimes referred to as a process information pseudo-file system. It doesn't contain 'real' files but runtime system information (e.g. system memory, devices mounted, hardware configuration, etc). For this reason it can be regarded as a control and information centre for the kernel. In fact, quite a lot of system utilities are simply calls to files in this directory. For example, 'lsmod' is the same as 'cat /proc/modules' while 'lspci' is a synonym for 'cat /proc/pci'. By altering files located in this directory you can even read/change kernel parameters (sysctl) while the system is running."
Source: https://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/proc.ht...
Sort of.
Some smaller Linux live CD / live USB distributions such as Damn Small Linux (DSL) (https://en.wikipedia.org/wiki/Damn_Small_Linux) and Puppy Linux (https://en.wikipedia.org/wiki/Puppy_Linux) had the option to load the entire distribution into memory (RAM disk) and run completely from memory.
This allowed them to run very fast since the entire base filesystem was in RAM and also be ephemeral since the filesystem would disappear on reboot or power off.
Your could still mount the computer's hard disk or other removable disks, but / was in RAM.
Other larger Linux live CD / live USB distributions such as Knoppix (https://en.wikipedia.org/wiki/Knoppix) would place a core portion of the system on a RAM disk and then read from the CD / USB to get other files as needed.
Plan 9 (https://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs) is not a Linux distro, but a Unix successor that extended the "everything is a file" Unix idea even further to allow multiple computers to act as one using the 9P protocol. This means that you could "mount" server _programs_ running on other computers somewhere under / and use file-like operations to interact with them. Almost like a REST API, but with 9P instead of TCP and file-like I/O instead of HTTP GET, PUT, and POST.
What's wrong with it being your main hard disk?
Backwards compatibility. I agree it is unfortunate.