Cloud computing refers to the delivery of computing services—including servers, storage, databases, networking, software, and more—over the internet ("the cloud") to offer faster innovation, flexible resources, and economies of scale. Instead of owning and maintaining physical data centers and servers, organizations can access computing resources on-demand from cloud service providers.

Key characteristics of cloud computing include:

On-Demand Self-Service: Users can provision computing resources, such as server instances or storage, as needed without requiring human intervention from the service provider.

Broad Network Access: Cloud services are accessible over the internet from various devices, such as laptops, smartphones, and tablets, using standard protocols and interfaces.

Resource Pooling: Computing resources are pooled together and shared among multiple users or tenants, allowing for efficient utilization and optimization of resources.

Rapid Elasticity: Cloud resources can be rapidly scaled up or down to meet changing demand, allowing organizations to adapt quickly to fluctuations in workload or user traffic.

Measured Service: Cloud usage is typically metered and billed based on actual consumption, allowing organizations to pay only for the resources they use.

Cloud computing can be categorized into several service models:

Infrastructure as a Service (IaaS): Provides virtualized computing resources, such as virtual machines, storage, and networking, on-demand over the internet. Users have control over the operating systems, applications, and development frameworks running on the infrastructure.

Platform as a Service (PaaS): Offers a platform for building, deploying, and managing applications without the complexity of managing underlying infrastructure. PaaS providers typically offer development tools, middleware, databases, and other services to support the entire application lifecycle.

Software as a Service (SaaS): Delivers software applications over the internet on a subscription basis, eliminating the need for users to install, manage, and maintain software locally. Examples include email services, customer relationship management (CRM) software, and productivity suites.