File System

Be sure to know these concepts, learn at your own pace:

File System Entries (File, Directory/Folder)
Disk
Path (Absolute, Relative)
The explorer application

You can use e.g. this link. You should really knows this at this point, so I won’t explain it.

Knowing these would be great, but it’s not required:

File System Tree (the idea of organizing file system entries in a tree)
Symbolic Links (Junctions)

Learn these if you’re interested:

File system formats (FAT32, NTFS, etc.)
Permissions in NTFS
Formatting drives
Fragmentation
Storage media (HDD, SSD, tape, etc.)
Backupping