Cloud computing was originally devised as an alternative to deploying racks of servers in company-owned (or shared) data centers. However, the technology services that have grown on top of the concept — to finally become quintessential to the concept — have changed the game.
The cloud stack: IaaS, PaaS, SaaS
Cloud technology is typically segmented into three layers, or service models:
- Infrastructure as a service (IaaS) provides infrastructure like physical computing resources, location, data partitioning, scaling, security, backup etc.
- Platform as a service (PaaS) offers a development and deployment environment to application developers.
- Software as a service (SaaS), sometimes referred to as on-demand software, provides access to application software for end-users.
While IaaS remains primarily a way for IT infrastructure to scale and adapt to changing requirements, the latter two (PaaS and SaaS) have become the key for companies to quickly build and deploy applications (and also complex business processes) that are easily and instantly accessible by users.