The brand was originally introduced by IBM in 1994 for enterprise-level HDDs together with home-computing oriented Deskstar model.
Western Digital continued using the HGST prefix on product labels, slowly phasing it out.
[1] The IBM's revolutionary technology of metal-coated glass plates initially was plagued with bad adhesion of the metal layer and its consequent delamination with irreparable disk failure.
This effectively decimates the promised 5-years warranty for drives purchased from the retailer stocks to shorter terms.
[2] After acquiring, Western Digital started shipping "Refurbished" and "Recertified" second-hand Ultrastar drives from data-centers cheaply in large amounts, which is actively used by the Internet cons, selling them as new.