Cloud Computing can be defined as using a network of remote servers hosted on the Internet to store, manage, and process data, instead of using local server or a personal computer. Companies offering these computing services are called cloud providers and typically charge for cloud computing services based on usage or service plans.

TYPES OF CLOUD SERVICES

Most cloud computing services fall into three broad categories:
1. Software as a service (Saas)
2. Platform as a service (PaaS)
3. Infrastructure as a service (IaaS)

These are sometimes called the cloud computing stack, because they are built on top of one another. Read below to learn which solution may be best for you.

1. SOFTWARE AS A SERVICE
Software-as-a-Service (SaaS) is a way of delivering services and applications over the Internet. Instead of installing and maintaining software, you simply access it via the Internet through your existing web-browser (Firefox, Google Chrome, Edge, Explorer etc.) SaaS frees you from involvement in complex software and hardware management. It removes the need to install and run applications on your computers or data center thus eliminating the expenses of hardware as well as software maintenance.
SaaS provides a complete software solution which you purchase on a pay-as-you-go basis from a cloud service provider. The SaaS applications are sometimes also referred to as Web-based software, on-demand software, or hosted software.

Advantages of SaaS :
1. Cost Effective: Pay only for what you use or at a “per user” rate.
2. Reduced time: Users can run most SaaS apps directly from their web browser without needing to download and install any software. This reduces the time spent in installation and configuration, and can reduce the issues that can get in the way of the software deployment.
3. Accessibility: You can access app data from anywhere as long as you have the required logon permissions and credentials.
4. Automatic updates : Rather than purchasing new software, customers rely on a SaaS provider to automatically perform the updates.
5. Scalability: It allows the users to access the services and features on demand and costs only increase or decrease based on amount of users
Examples of companies providing software as a service are, Microsoft, Adobe, Dropbox, Amazon Web Services, Google and more.

2. PLATFORM AS A SERVICE
PaaS is a category of cloud computing that provides a platform and environment to allow developers to build applications and services over the internet. The user/consumer does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly configuration settings for the application-hosting environment.

Advantages of PaaS :
1. Simple and convenient for users: It provides much of the infrastructure and other IT services, which users can access anywhere via a web browser.
2. Cost Effective: It charges for the services provided on a per-use basis thus eliminating the expenses one may have for on-premises hardware and software.
3. Efficiently managing the lifecycle: It is designed to support the complete web application lifecycle: building, testing, deploying, managing and updating.
4. Efficiency: It allows for higher-level programming with reduced complexity thus, the overall development of the application can be more effective
The various companies providing PaaS are Amazon Web services, Salesforce, Windows Azure, Google App Engine, cloud Bess and IBM smart cloud.

3. INFRASTRUCTURE AS A SERVICE
Infrastructure as a service (IaaS) is a service model that delivers computer infrastructure on an outsourced basis to support various operations. Typically IaaS is a service where infrastructure is provided as an outsource to enterprises such as networking equipment, devices, database and web servers.

Infrastructure as a service (IaaS) is also known as Hardware as a service (HaaS). IaaS customers pay on a per-use basis, typically by the hour, week or month. Some providers also charge customers based on the amount of virtual machine space they use.
It simply provides the underlying operating systems, security, networking, and servers for developing such applications, services, and for deploying development tools, databases, etc.

Advantages of IaaS :
1. Cost Effective: Eliminates capital expense and reduces ongoing cost and IaaS customers pay on a per use basis, typically by the hour, week or month.
2. Website hosting: Running websites using IaaS can be less expensive than traditional web hosting.
3. Security: The IaaS Cloud Provider may provide better security than your existing software.
4. Maintenance: There is no need to manage the underlying data center or the introduction of new releases of the development or underlying software. This is all handled by the IaaS Cloud Provider.
The various companies providing Infrastructure as a service are Amazon web services, Bluestack, IBM, Openstack, Rackspace and Vmware.