On Windows, open Settings > System > About and look for Device name
On Windows, press Windows + Pause/Break and check Computer name
On Windows, open Command Prompt and type hostname
On Windows, open Command Prompt and type echo %computername%
On Mac, open System Settings > General > About and look for Name
On Mac, open Terminal and type scutil –get ComputerName
On Linux, open Terminal and type hostname
On Linux, open Terminal and type uname -n
On Linux, open Terminal and type cat /etc/hostname