A public cloud refers to cloud services operated by cloud providers and made widely available to the general public. Examples of this include Amazon Web Services (AWS) and Microsoft Azure.
Public clouds offer the benefit of not requiring user organizations to prepare their own hardware. Additionally, operations are handled by the cloud provider, allowing organizations to save on initial investment and setup time, while also reducing operational burdens. However, because public clouds often run on a pay-as-you-go pricing model, the total cost can increase when handling high-intensity workloads. Furthermore, entrusting a cloud provider with the management of sensitive information may raise security concerns in some cases.
In contrast, a cloud that is built and operated by the user organization itself is referred to as a private cloud. The data center used for this purpose may either be owned by the organization or leased from a data center provider. While user organizations are responsible for building and operating the private cloud system, resulting in higher initial investments, longer setup times, and greater operational burdens, private clouds offer the advantage of easier security management. Additionally, private clouds are necessary when working with software that is not designed to be used on public cloud platforms.
Recently, a hybrid cloud approach that combines these two types of clouds has been gaining popularity. This approach aims to optimize systems by leveraging the advantages of both cloud types. For example, applications with significant workload fluctuations can run on a public cloud, while those with stable workloads can run on a private cloud, thereby optimizing overall costs. Similarly, web applications intended for external use can be hosted on a public cloud, while applications that handle sensitive information can be kept within a private cloud.