IaaS, or Infrastructure as a Service, is a cloud computing model that provides virtualized computing resources over the internet. Instead of investing in physical hardware, businesses can rent servers, storage, and networking from a cloud provider. This allows companies to scale their IT resources up or down based on their needs, making it a flexible and cost-effective solution. With IaaS, users can manage their operating systems and applications while the cloud provider takes care of the underlying infrastructure. This means businesses can focus on their core activities without worrying about hardware maintenance or upgrades, leading to increased efficiency and innovation.