Software-defined data center (SDDC; also: virtual data center, VDC) is a marketing term that extends virtualization concepts such as abstraction, pooling, and automation to all data center resources and services to achieve IT as a service (ITaaS). In a software-defined data center, "all elements of the infrastructure — networking, storage, CPU and security – are virtualized and delivered as a service."

SDDC support can be claimed by a wide variety of approaches. Critics see the software-defined data center as a marketing tool and "software-defined hype," noting this variability.

In 2013, analysts were divided into three different groups, those who think it is "just another software-defined hype", those who think most of the components are already available and those who see a potential future market. There was no unified agreement about the direction of SDDC. For some areas like the software-defined networking a market value of about US$3.7 billion by 2016 was expected, compared to US$360 million in 2013. (software-defined networking was expected to reach US$18.5 billion in 2022) IDC estimates that the software-defined storage market is poised to expand faster than any other storage market.

The software-defined data center encompasses a variety of concepts and data-center infrastructure components, with each component potentially provisioned, operated, and managed through an application programming interface (API). Core architectural components that comprise the software-defined data center include the following:

A software-defined data center differs from a private cloud, since a private cloud only has to offer virtual-machine self-service, beneath which it could use traditional provisioning and management. Instead, SDDC concepts imagine a data center that can encompass private, public, and hybrid clouds.

Data centers traditionally lacked the capacity to accommodate total virtualization. By 2013, companies began laying the foundation for software-defined data centers with virtualization. Ben Cherian of Midokura considered Amazon Web Services as a catalyst for the move toward software-defined data centers because it "convinced the world that the data center could be abstracted into much smaller units and could be treated as disposable pieces of technology, which in turn could be priced as a utility."

In 2013, the software-defined data center term was promoted as a paradigm shift. According to Steve Herrod, the promise of the software-defined data center was that companies would no longer need to rely on specialized hardware or hire consultants to install and program hardware in its specialized language. Rather, IT would define applications and all of the resources they require—including compute, storage, networking, security, and availability—and group all of the required components to create a “logical application.”

Commonly cited benefits of software-defined data centers include improved efficiency from extending virtualization throughout the data center; increased agility from provisioning applications quickly; improved control over application availability and security through policy-based governance; and the flexibility to run new and existing applications in multiple platforms and clouds.