Hello and welcome to this lecture aimed at providing you with an understanding of some of the concepts which make cloud technology so important. Cloud computing has a number of key characteristics that allow it to be the powerful service that is it today, and it's a good idea to have an understanding and awareness of these and what they offer. On-demand resourcing. This essentially means that when you want to provision a resource within the cloud, it's almost immediately available to you to allocate where and when you need it. No more waiting around for hardware to be ordered, installed, cabled, and configured before using it. Scalability. 

Cloud computing offers you the ability to rapidly scale your environment's resources both up and down and in and out, depending on your requirements and demands of your application and services. When scaling up and down, you effectively alter the power and performance of an instance, perhaps using one with a greater CPU or memory power. When scaling in and out, you are simply adding or removing the number of instances you're using to your fleet of compute resources. This offers a significant advantage compared to on-premise solutions, from a cost-perspective alone. Economy of scale. 

Due to the huge scale of resources public cloud offerings provide, which are optimized and shared between different organizations, thanks to virtualization technology, you as the end user benefit from exceptionally low resource costs compared to traditional hosting. Flexibility and elasticity. Cloud computing offers huge flexibility and elasticity to your design approach. You can choose to have as many or as few resources as you require. You decide how much and how long you want it for, and at what scale. 

The amount of choice you have allows you to fully customize exactly how you want and need your environment, using only the resources required. Growth. Cloud computing offers your organization the ability to grow using a wide range of resources and services. Couple with the on-demand element, and your growth constraints are significantly reduced compared to a classic on-premises environment. This growth also includes the ability to reach global customers with ease, by provisioning resources across the cloud vendor's global network. Utility-based metering. 

With many cloud services, you only pay for what you use. What do I mean by this? If you only have an instance running for two hours, and then shut it down, then you only pay for two hours worth of compute resources, and that's it. Think of it like this. In your house, you only pay for your electricity when you use it, and to help keep costs down, you turn off the lights when you're not using them. So it's the same billing process for many resources and services. You only pay for resources when you are using them. Shared infrastructure. 

As discussed previously, during the virtualization section, hosts within the cloud are virtualized. As a result, multiple tenants can be running instances on the same piece of hardware. This significantly reduces the amount of physical hardware required, which in turn reduces the amount of power, cooling, and space required in the data center. And in turn, helps with the economy of scale, all resulting in cheaper costs to you as the customer. Highly available. By design, many of the core services within the public cloud and its underlying infrastructure are replicated across different geographic zones and regions. 

Having data copied to multiple different places automatically, helps you to ensure the durability and availability of your data and services, without even having to configure and architect for this resilience. It's provided by the vendor as a part of their service. Security. 

This is one of the most discussed topics within cloud computing, and many enterprises still have concerns over how secure it is. However, public cloud vendors such as AWS and Microsoft Azure are considered to be more secure than your own data center. This is down to the fact that they have to adhere to global compliance programs across multiple industries and by applying the shared responsibility model. The vendor will operate to an exceptionally high standard of security for the underlying infrastructure of the cloud, and it's down to you, the end user, to then architect security in the cloud, using the tools, services and applications available. 

For more information on the shared responsibility model for Amazon Web Services, please take a look at our existing blog here. These are just some of the key characteristics of cloud computing, and you can see how differently it operates from your traditional on-premise data center deployments that you may be using today. That now brings me to the end of this lecture. Next I'll be looking at the different cloud service models available.