Infrastructure as a service, or IaaS for short, is a service where a provider rents out its own IT infrastructure and makes it available to use online. To do this, the cloud provider usually operates its own data centers where the corresponding hardware is stored, administered, and maintained. By doing this, IaaS providers can offer access to computing power (processor, memory, hard drive space) and complete network structures (including firewalls, routers, and security/back-up systems), the scope of which you, as a customer, can freely dispose of. You can choose which infrastructure you want to use, how many servers, routers, firewalls you want to use, and what performance data (CPU, RAM, etc.) the various network elements should have.
The rented IaaS resources can be scaled up or down at any time if you want to integrate an additional server or reduce the computing power. With most providers, however, you only pay for the components that you actually use. This high flexibility results from the fact that infrastructure as a service offers are generally not bound to dedicated hardware, which allows the provider to distribute its data center resources among its customers as optimally as possible. To ensure reliability and security of its service in the long run, the provider also takes care of the maintenance and modernization of data center hardware and the installation of relevant security systems and devices. Of course, this also includes replacing defective parts.