List the main functions of an operating system. Describe any three system tools provided by Windows operating system.

An OS (Windows, Linux) manages resources and bridges user and hardware.

Main functions:

1. Process management — Schedules CPU, multitasking (Word + print + scan together).
2. Memory management — Allocates RAM, virtual memory, isolates programs.
3. File management — Folders, naming, search, NTFS permissions.
4. Device management — Drivers, spooling/buffering (print queue).
5. Security — Accounts, passwords, access rights, logs.

Three Windows system tools:

1. Disk Defragmenter (Optimize): Rejoins scattered HDD fragments into continuous blocks for faster boot/open. SSDs use Trim, auto-weekly.
2. System Restore: Rolls system files to earlier restore point after bad driver/update, keeping personal files safe. Control Panel → Recovery → choose date.
3. Disk Cleanup (+ Backup): Deletes temp/recycle files to free GBs; Backup and Restore keeps scheduled copies for recovery after failure.

Exam tip: functions = what OS does; tools = how we maintain it.