Your product's model number is essentially its name. It's a combination of letters and numbers, e.g.: DSC-TW10& PCG-682L& or KDF-55E2000.

You can find it in a variety of places (depending on the product type):

In the accompanying documentation (manuals, warrantee, etc.)

On the product itself, as part of the product's logo.

On an information sticker or panel affixed to the back or underside of product, or within a battery or power cord compartment.