Cloud computing has a number of key characteristics that allows it to become the powerful service that it is today. Let's go through the main ones.

On-demand resourcing. This essentially means that when you want to provision a resource within the cloud, it's almost immediately available to you. You allocate them when and where you need them. There's no more waiting around for hardware to be ordered, installed, cabled, and configured before you can use it. It's often as simple as filling out a form and clicking submit.

Consumption-based. With many cloud services, you only pay for what you use. What do I mean by this? Well, if you only have a server running for two hours and then you shut it down, then you're only going to pay for two hours worth of compute resources. It's just like your power bill at home and how you only pay for the electricity you use.

Scalability and agility. Cloud computing offers you the ability to rapidly scale your environment's resources, both up and down and in and out. It depends upon the requirements and the demands of your application and services. When scaling up and down, you're altering the power and performance of a particular instance. Perhaps you're using one with greater CPU or memory power. When scaling in and out, you're simply adding or removing instances to your fleet of compute resources. This gives you the ultimate flexibility to keep up with the ever-changing demands of the market. And it frees you up to try new things and experiment with much lower initial costs.

Economy of scale. Public cloud vendors can procure hardware for much cheaper due to bulk pricing. Also, it's simply more economical to create and run large public cloud data centers rather than having each company with its own on premises. You, as the end user can benefit from these exceptionally low resource costs compared to traditional hosting.

Highly available. By design, many of the core services on the public cloud are replicated across different geographic zones and regions. That means that a disruption in one area does not have to result in any downtime. When one zone goes down, you can usually seamlessly switch to another. In this way, you can ensure the durability of your data and the availability of your services.

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. You have full control and can make fairly significant changes without worrying about waste.

Shared infrastructure. As discussed previously, multiple instances running on the same hardware significantly reduces the amount of physical hardware required. This in turn reduces the amount of power, cooling, and space required. All this results in cheaper costs for you, the customer.

Security. Now, this is one of the most discussed topics within cloud computing and many enterprises still have concerns. However, the major public cloud vendors are considered to be more secure than your own data center. The main vendors operate at an exceptionally high standard of security. They manage the security of the cloud by securing the data centers. And it's up to you to ensure security in the cloud by correctly leveraging the tools, services, and applications available. If you copy your private information to a publicly accessible website, that's on you. These are just some of the key characteristics of cloud computing. There are more, but these are typically the most important.