steamservice

steamservice.exe is the Windows service that backs Steam's elevation-requiring operations (privileged installs, certain driver registrations, system-wide configuration). It runs as a service alongside the main user-mode steam.exe and steamwebhelper.exe processes, so a casual user rarely interacts with it directly.

If Steam is installed, this service is expected. Disabling it breaks some Steam features; the supported way to remove it is to uninstall Steam.