Operating Systems and File Management
What to know
The operating system is the layer between hardware and applications. It manages processes (starting, scheduling and stopping programs), allocates memory, provides the file system, loads device drivers, handles input and output, and presents a user interface, either graphical (GUI) or command line (CLI). Multi-tasking, multi-user and real-time are categories of OS, not brands. On startup the firmware runs a power-on self-test, locates the boot device and loads the OS kernel.
A file has a name, an extension that tells the OS which program should open it, a location (path), a size and attributes such as read-only or hidden. Folders group files and build the path, for example C:\Users\Ana\Docs\report.docx. Copy duplicates a file and leaves the original in place; move relocates it and leaves none behind, and within one drive a move is effectively a rename and is fast. Deleting normally sends an item to the Recycle Bin or Trash, from which it can be restored; emptying the bin, or deleting from a network or removable drive, may bypass it. Uninstalling removes a program and its registry entries, while deleting its folder does not.
Traps
The extension does not guarantee content: renaming a .txt file to .docx does not convert it. A shortcut is a pointer, not the file itself. Moving across drives is a copy-then-delete, so it is slower than a same-drive move. Hidden and system files still exist when they are not displayed.
Worked example
For the path C:\Work\Q3\budget.xlsx, read from the right: the file is budget.xlsx, its folder is Q3, which sits inside Work.