Linux manages all filesystems as a single large tree. This is unlike DOS, which manages all hard drives and network volumes as a set of independent units (C: D: E:).
The first partition accessed by Linux is called the root.
The top-level directory is called /. The other
partitions (and network volumes) may be installed anywhere
in the filesystem tree.
For example, you can set up your Linux system like this:
These directories are called "mount points". They are initially empty. Linux will logically install the different partitions and volumes right there.
All this means is that you have to tell Linux which partitions/volumes go where.