Most people by now have a sense of what clouds are. When IT services and resources are hosted offsite somewhere else, they are often in clouds. But clouds have certain characteristics that define them, as opposed to simple offsite hosting. Clouds are elastic in that their services can scale up and down according to their customers’ needs. When you require additional storage, for example, you can get more capacity quickly and easily in a cloud. Conversely, you can flexibly decrease capacity. By extension, clouds have billing and metering of service usage so you pay only for what you use. Additionally, your users, such as workgroups, have self-service provisioning that enables them to rapidly obtain resources for projects or other needs. These functionalities make clouds flexible, cost-effective, and attractive for many enterprises.

There are several kinds of clouds, however, and some are more appropriate for particular circumstances than others. Public clouds are virtualized data centers outside of their customers’ private networks. Companies access their resources via the Internet and these resources reside on virtualized servers that share physical devices with other customers in what is known as a multi-tenant architecture. Public clouds are useful for enterprises with distributed employees working collaboratively on projects, or for testing and developing applications.

However, although many enterprises value the versatility offered by clouds, they are wary of security concerns when their precious data must traverse the Internet to be hosted offsite by third parties. This has led to the rise of private clouds, which have the characteristics of public clouds but are hosted locally within a company’s data center(s). Enterprises must buy and manage their cloud resources, which can be costlier than outsourcing to public clouds. But companies also have greater control over their data and applications, and because everything is behind their firewalls, they can enjoy greater security. Private clouds are appropriate in industries with stringent regulatory requirements.

Many companies are turning to a combination of public and private clouds in a model appropriately called hybrid clouds. Hybrid clouds enable businesses to keep vital resources like financial and proprietary data local in private clouds within the company firewalls, but they permit the outsourcing of less sensitive functions like email services to public clouds for cost savings. Moreover, they allow cloud bursting to meet spikes in demand. When seasonal sales or major projects exceed the compute or storage capabilities of the private cloud, public clouds can be called upon temporarily to meet the extra demand.

The bottom line is clouds not only offer remarkable flexibility, but they also can be flexibly deployed depending on each company’s needs and resources.