ZDNet is a business technology news website published by CBS Interactive, along with TechRepublic and SmartPlanet. The brand was founded on April 1, 1991 as a general interest technology portal from Ziff Davis and evolved into an enterprise IT-focused online publication owned by CNET Networks.

ZDNet began as a subscription-based digital service called "ZiffNet" that offered computing information to users of CompuServe. It featured computer industry forums, events, features and searchable archives.

Initially, ZiffNet was intended to serve as a common place to find content from all Ziff-Davis print publications. As such, ZiffNet was an expansion on an earlier online service called PCMagNet for readers of PC Magazine. Launched in 1988, PCMagNet in turn was the evolution of Ziff Davis' first electronic publishing venture, a bulletin board, which launched in 1985.

On June 20, 1995, Ziff-Davis announced the consolidation of its online information services under a single name, "ZD Net." The service had grown its membership to 275,000 subscribers across six platforms: CompuServe, Prodigy, AT&T Interchange, the Microsoft Network, AppleLink and eWorld.