PURPOSE A serial number uniquely identifies a device for support, warranty, inventory, or replacement. WHERE TO LOOK Check the physical label, system information, device settings, original packaging, or manufacturer support tool. COPY CAREFULLY Serial numbers can include similar-looking letters and numbers. Double-check O and zero, I and one, and S and five. WHEN TO PROVIDE IT Include it when reporting hardware failures, warranty issues, lost devices, or replacement requests. CAUTION Do not publicly post serial numbers unless required.