What is a Public Cloud? - In a public cloud, a third-party provider offers a range of services to the general public over the internet. Data from several corporate or individual clients may share the same server. A private cloud is similar in principle, but is set up behind a firewall and provides hosted services to only a limited number of approved users. Public clouds can offer the replication of data to many locations, and thus organizations with users all over the world can use public clouds as an alternative to content distribution networks. Because public clouds are accessed over the internet, they may be subject to bandwidth limitations, whereas private clouds are accessed over the Ethernet LAN at high speed.
The most salient examples of cloud computing tend to fall into the public cloud model because they are, by definition, publicly available. Software as a Service (SaaS) offerings such as cloud storage and online office applications are perhaps the most familiar, but widely available Infrastructure as a Service (IaaS) and Platform as a Service (PaaS) offerings, including cloud based web hosting and development environments, can follow the model as well (although all can also exist within private clouds). Public clouds are used extensively in offerings for private individuals who are less likely to need the level of infrastructure and security offered by private clouds. However, enterprise can still utilise public clouds to make their operations significantly more efficient, for example, with the storage of non-sensitive content, online document collaboration and webmail.
These are based on shared physical hardware which is owned and operated by third-party providers, meaning that there are no hardware or maintenance costs incurred by your business. The ideal solution for small to medium sized businesses or those that have fluctuating demands, the primary benefits of the public cloud are the speed with which you can deploy IT resources, and the utility billing it offers. By spreading infrastructure costs are across a number of users, each can operate on a low-cost, pay as you go approach to the provisioning of IT services. And, due to the sheer size of public clouds, businesses can scale compute power up and down as changing business demands dictate, within a matter of minutes.
The public cloud represents a convenient and cost-effective solution for a wide range of storage needs. It is best used for personal data and non-sensitive information, because its biggest drawback is the potential security risks. For large amounts of data or if you have a slow internet connection, speed of access may also be an issue.
If your organisation deals with any amount of sensitive data, though, a different solution will be preferable. A private cloud eliminates the risks of handing your data over to a third party, but comes with greater expenses and maintenance requirements. A hybrid cloud allows the best of both worlds, by enabling you to save critical data locally on your secure server, and taking advantage of the economies of scale offered by the public cloud for large amounts of less sensitive material.