Multicloud is the use of multiple cloud computing and storage services in a single heterogeneous architecture. This also refers to the distribution of cloud assets, software, applications, etc. across several cloud-hosting environments. With a typical multicloud architecture utilizing two or more public clouds as well as multiple private clouds, a multicloud environment aims to eliminate the reliance on any single cloud provider. It differs from hybrid cloud in that it refers to multiple cloud services rather than multiple deployment modes (public, private, legacy). Also, in a multicloud environment, synchronization between different vendors is not essential to complete a computation process, unlike parallel computing or distributed computing environments.
For example, an enterprise may concurrently use separate cloud providers for infrastructure (IaaS), platform (PaaS) and software (SaaS) services, or use multiple infrastructure (IaaS) or platform (PaaS) providers. In the latter case, they may use different infrastructure providers for different workloads, deploy a single workload load balanced across multiple providers (active-active), or deploy a single workload on one provider, with a backup on another (active-passive).
There are a number of reasons for deploying a multicloud architecture, including reducing reliance on any single vendor, cost-efficiencies, increasing flexibility through choice, adherence to local policies that require certain data to be physically present within the area/country, geographical distribution of processing requests from physically closer cloud unit which in turn reduces latency, and militating against disasters. It is similar to the use of best-of-breed applications from multiple developers on a personal computer, rather than the defaults offered by the operating system vendor. It is a recognition of the fact that no one provider can be everything for everyone. Various issues and challenges also present themselves in a multicloud environment. Security and governance is more complicated, and more "moving parts" may create resiliency issues. Selection of the right cloud products and services can also present a challenge, and users may suffer from the paradox of choice. However, in 2019 April Google announced releasing Anthos, which can manage workloads on third-party clouds, including Amazon Web Services and Microsoft Azure  and in the late 2020 Techcrunch announced new independent multi cloud management platform CAST AI entering the market, additionally offering cost optimisation, so developers will be able to get the best of each of the public clouds without being locked in.
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