Infrastructure as a Service (IaaS) is one of the three main categories of cloud computing services, alongside Software as a Service (SaaS) and Platform as a Service (PaaS). IaaS provides users with virtualized computing resources over the internet.

• IaaS platforms offer highly scalable resources that can be adjusted on-demand. This makes IaaS well-suited for workloads that are temporary, experimental, or change unexpectedly.
• With IaaS, you rent IT infrastructure - servers and virtual machines (VMs), storage, networks, and operating systems - from a cloud provider on a pay-as-you-go basis.
• IaaS allows businesses to scale up and down quickly in response to demand, and they only pay for what they use.

IaaS works by providing all the infrastructure to support web apps, including storage, web and application servers, and networking resources. Users can get to their applications faster, without the need for deep architectural discussions, capacity planning, and vendor negotiations that purchasing hardware and software require.

• IaaS is used in a variety of use cases, from hosting websites to analyzing big data.
• IaaS provides a complete infrastructure, including provisioning, managing, and maintaining the physical hardware in the data center.
• Users can access, monitor, and manage their infrastructure remotely.

A startup company wants to launch a web application but doesn't have the capital to invest in expensive hardware and software. Instead, they turn to an IaaS provider who provides the necessary infrastructure on a pay-as-you-go basis. The startup can then focus on developing their web application without worrying about purchasing, setting up, or maintaining physical servers.

• For instance, during a sudden spike in user traffic, the startup can easily scale up resources to maintain performance and user experience.
• When the traffic decreases, they can scale down again to minimize costs, demonstrating the flexibility and cost-effectiveness of IaaS.