1.  What is Virtualization?
It is the process of creating a virtual version of something like computer hardware. It involves using specialized software to create a virtual or software-created version of a computing resource in place the actual version of the same resource. With the help of Virtualization, multiple operating systems and applications can run on the same machine and its same hardware at the same time, increasing the utilization and flexibility of hardware. 
That is to say, it is one of the major economical, hardware-reducing, and energy-efficient approach used by cloud providers

2.Scalability:
the ability of an organization (or a system, such as a computer network) to perform well under an increased or amplifying workload.
Hence, it is the ability to increase or decrease IT resources as needed to meet changing demand
3.Agility
the ability to quickly develop, test, and launch applications in a cloud-based environment.

4.High Availability:
means that an IT system, component, or application have the ability to operate at a high level, continuously, without intervention, for a given time period,
a quality of computing infrastructure that allows it to continue functioning, even when some of its components fail.
High Availability in cloud computing is the ability of a system or application to remain accessible and operational for a long period of time. It is a key characteristic of cloud services that ensures they can handle different load levels and recover quickly from any failures.

5.Fault Tolerant:
a process that enables an operating system to respond to a failure in hardware or software. This fault-tolerance definition refers to the system's ability to continue operating despite failures or malfunctions.
It is about designing a blueprint for continuing the ongoing work whenever a few parts are down or unavailable. This helps the enterprises to evaluate their infrastructure needs and requirements, and provide services when the associated devices are unavailable due to some cause.

6.Global Reach:
The cloud transcends geographical boundaries, enabling organizations to establish a global footprint without the constraints of physical infrastructure. its ability to have customers in many different parts of the world without the restraint of of physical facilities.

7.What is the difference between Elasticity and Scalability
Basically, scalability is about building up or down, like someone would with, say, a Lego set. Elasticity, meanwhile, entails stretching the boundaries of a cloud environment, like you would stretch a rubber band, to ensure end users can do everything they need, even in periods of immensely high traffic.
Elasticity refers to how fast your application can scale up or down based on demand, while scalability refers to how the system can handle much load. Elasticity and scalability are two critical factors to consider when building your application on the cloud.