The URL http://www.hp.com/go/extendedwarranty is the official HP webpage to register for and purchase extended warranty and support plans, commonly called HP Care Packs, for HP products like printers. This site allows customers to extend warranty coverage beyond the standard warranty period, providing benefits such as next-business-day replacement, free repairs including parts and labor, and remote diagnosis support[1][2][5].

Specifically, for HP printers, registering within 60 days of purchase and uploading proof of purchase can grant access to an HP 2-Year Next Business Day Exchange Care Pack, which covers repairs or replacements with fast service[5]. Some promotions, like for HP Smart Tank printers, also allow free one-year warranty extensions through registration via this link[1].

More generally, HP Care Packs are available for printers and PCs, offering 1- to 4-year extended protection plans with additional options like accidental damage and theft protection for PCs[2][4]. These services provide convenient support seven days a week and cover costs such as return shipping[2].

In summary, http://www.hp.com/go/extendedwarranty is the official HP page to register and manage extended warranty services and support plans for HP devices, ensuring extended protection after the standard warranty expires[1][2][5].