How to Locate the Serial Number of Windows Machine
Open the Command Prompt by pressing the Windows key on your keyboard, then pressing X. Select Command Prompt (Admin) on the menu.
Type wmic bios get serialnumber and then press Enter on your keyboard.
The serial number will be shown on the screen.
How to Locate the Serial Number of MAC :
About This Mac
From the Apple menu in the corner of your screen, choose About This Mac. Then find the serial number in the information shown.
Press and hold the Option key on your keyboard while choosing Apple menu > System Information from the menu bar.
Select Hardware in the sidebar.
Find the model name and serial number on the right.
You can also have System Information read your serial number out loud. From the menu bar in System Information, choose File > Speak Serial Number. Or press Command-4.
Tip: You can also have System Information read your serial number out loud. From the menu bar in System Information, choose File > Speak Serial Number. Or press Command-4.
Go to Utilities. Open the Terminal application and type:
ioreg -l | grep IOPlatformSerialNumber
With the release of macOS Ventura (Version 13), to find this information outside of the above, there are now two separate ways to find your serial number:
How to Locate the Serial Number of LINUX:
Open a shell and type:
sudo dmidecode -t system | grep Serial
Note: The user will need to have root access to the system.