Cloud computing is the the use of various services, such as software development platforms, servers, storage and software, over the internet, often referred to as the "cloud."
In general, there are three cloud computing characteristics that are common among all cloud-computing vendors:
The back-end of the application (especially hardware) is completely managed by a cloud vendor.
A user only pays for services used (memory, processing time and bandwidth, etc.).
Services are scalable
Example: AWS, Azure, Google Cloud
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Working Model of Cloud
There are certain services and models working behind the scene making the cloud computing feasible and accessible to end users. Following are the working models for cloud computing:
Deployment Models
Service Models
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Deployment models define the type of access to the cloud, i.e., how the cloud is located? Cloud can have any of the four types of access:
Public
Private
Hybrid
Community
Deployment Models
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PUBLIC CLOUD
The public cloud allows systems and services to be easily accessible to the general public. Public cloud may be less secure because of its openness.
PRIVATE CLOUD
The private cloud allows systems and services to be accessible within an organisation. It is more secured because of its private nature.
COMMUNITY CLOUD
The community cloud allows systems and services to be accessible by a group of organisations.
HYBRID CLOUD
The hybrid cloud is a mixture of public and private cloud, in which the critical activities are performed using private cloud while the non-critical activities are performed using public cloud.
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Service Models
Cloud computing is based on service models. These are categorized into three basic service models which are -
Infrastructure-as–a-Service (IaaS)
Platform-as-a-Service (PaaS)
Software-as-a-Service (SaaS)
Infrastructure-as-a-Service (IaaS)
IaaS provides access to fundamental resources such as physical machines, virtual machines, virtual storage, etc.
Platform-as-a-Service (PaaS)
PaaS provides the runtime environment for applications, development and deployment tools, etc.
Software-as-a-Service (SaaS)
SaaS model allows to use software applications as a service to end-users.
