What is Platform as a Service (PaaS)?

Platform as a Service (PaaS) is a category of cloud computing services that provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically associated with developing and launching an app. PaaS can be delivered in three ways:

• As a public cloud service from a provider, where the consumer controls software deployment with minimal configuration options, and the provider provides the networks, servers, storage, operating system (OS), middleware (e.g. Java runtime, .NET runtime, integration, etc.), database and other services to host the consumer's application.
• As a private service (software or appliance) inside the firewall.
• As software deployed on a public infrastructure as a service.

Like IaaS, PaaS includes infrastructure (servers, storage and networking) and also middleware, development tools, business intelligence (BI) services, database management systems and more. PaaS is designed to support the complete web application life-cycle: building, testing, deploying, managing and updating. The advantages of PaaS are as follows:

• Cut coding time.
• Add development capabilities without adding staff.
• Develop for multiple platforms, including mobile, more easily.
• Use sophisticated tools affordably.
• Support geographically distributed development teams.
• Efficiently manage the application life-cycle.

What is Software as a Service (SaaS)?

Software as a service (SaaS) is a software licensing and delivery model in which software is licensed on a subscription basis and is centrally hosted. It is also referred to as "on-demand software", "web-based software" or "hosted software". SaaS is typically accessed by users using a thin client via a web browser and is considered to be one of the three pillars of Cloud Computing.

Instead of installing and maintaining software, customers simply access it via the Internet, thereby freeing themselves from complex software and hardware management. The provider manages access to the application, including security, availability, and performance.

SaaS provides a complete software solution which customers purchase on a "pay-as-you-go" basis from a cloud service provider. All of the underlying infrastructure, middleware, app software and app data are located in the service provider’s data center. SaaS allows an organisation to get up and running quickly with an app with minimal upfront cost.

There are many well-known examples of SaaS, including Office 365, Google Apps, Salesforce, Citrix GoToMeeting, Cisco WebEx and Netflix.

Some examples of where SaaS can be used by enterprises are as follows:

• Accounting and invoicing
• Tracking sales
• Planning
• Performance monitoring
• Communications (including webmail and messaging)
• Analytics

What is Infrastructure as a Service (IaaS)?

Infrastructure as a service (IaaS) is a service model of Cloud Computing that delivers computer infrastructure on an outsourced basis to support enterprise operations. Typically, IaaS provides hardware, storage, servers and data center space or network components; it may also include software.

An IaaS provider provides policy-based services and is responsible for housing, operating and maintaining the equipment it provides for a client. Clients usually pay on a per-use or utility computing basis.

Characteristics of IaaS include:

• Automated administrative tasks
• Dynamic scaling
• Platform virtualization
• Internet connectivity

IaaS helps the client avoid the expense and complexity of buying and managing one's own physical servers and other datacenter infrastructure. Each resource is offered as a separate service component and the client only needs to rent a particular one for as long as required.

The client does not manage or control the underlying cloud infrastructure but has control over operating systems, storage, and deployed applications; and possibly limited control of select networking components (e.g., host firewalls).

What is Cloud Computing?

Cloud computing is a concept that enables ubiquitous access to shared pools of configurable system resources and higher-level services that can be rapidly provisioned with minimal management effort, often over the Internet from multiple cloud server farms. Cloud computing relies on sharing of resources to achieve coherence and economies of scale, similar to a public utility.

Third-party clouds enable organizations to focus on their core businesses instead of spending resources on computer infrastructure, security and maintenance. Advocates of Cloud Computing note that this type of service allows companies to avoid or minimize up-front IT infrastructure costs and provides a robust, secure and flexible platform for businesses and individuals to run their IT operations. Minimum management, optimized resources and significantly less operational costs are some of the key benefits of the Cloud Computing platform. It also enables IT teams to more rapidly adjust resources to meet fluctuating and unpredictable demand. Cloud providers typically use a "pay-as-you-go" model which offers flexibility and reduces overhead costs, but which can also lead to unexpected operating expenses if administrators are not familiarized with cloud-pricing models.

This popular service can primarily be classified as Infrastructure as a Service (IaaS), Platform as a Service (PaaS) and Software as a Service (SaaS). There are several popular cloud computing providers in the market at present, of which, Amazon Web Services (AWS), Google Cloud Platform (GCP) and Microsoft Azure are the most popular.