What is a hybrid cloud architecture?

A hybrid multi cloud architecture combines public and private clouds over a wide area network or broadband connection, through which applications and data can be shared and managed as a single IT architecture. A hybrid cloud infrastructure is well suited to fluctuations in computing resource requirements because it enables businesses to scale from on-premises to public cloud-based clouds to meet growing demand, and scale back from public cloud to on-premises (private cloud) only once demand subsides.

Many organizations leverage public cloud infrastructure as a service (IaaS) for some workloads while keeping others in private clouds, whether for cost, compliance or technical reasons. The most common public IaaS providers are Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform.

Hybrid cloud architectures are becoming increasingly popular with enterprises, especially medium and large enterprises, who often rely on private clouds for legacy infrastructure and mission-critical applications, with 74% of enterprises saying they have a hybrid cloud environment in 2018.
What are the advantages of a hybrid cloud architecture?

Scalability: Organizations can leverage the economics of cloud-based backup and disaster recovery without having to maintain off-site facilities to handle IT in the event of a disaster. In the event of an outage in the primary data center or private cloud, snapshots stored in the public cloud can be "booted up" and those applications can be resumed with minimal disruption.
Flexibility: When demands change rapidly, such as during the holiday shopping season or due to a sudden successful product launch, organizations can "cloud burst" from private clouds to public cloud providers to support ever-increasing customer- and business-facing workloads - Key applications.
Seamless Migration: Hybrid cloud architectures allow enterprises to migrate front-end and stateless applications to the cloud first, then bring in other applications as virtual machines or modern containerization, while still retaining legacy on-premises servers and applications to which data cannot migrate Whether it's due to regulatory, governance, or other issues.
Cost Savings: Adopting a hybrid approach enables enterprises to take advantage of CSP economies of scale, especially for long-term archiving, backup, disaster recovery and business continuity.