"Cloud computing is a network of computing resources, that are delivered to various customers as a service over internet. Resources are available dynamically to the users; On the other hand provisioning of resources in a dynamic manner makes resource provision task more complex for scientists. As a result allocation of these resources plays a vital role in management of resources. In collaborative cloud environment, various cloud resources from different cloud servers are connected together to offer undisrupted service to consumers. Enhanced resource scheduling techniques are necessary to preserve separation among resource users. We require a resource provisioning model that will improve cloud system usability and reliability along with quality of service. In our paper we will review the work carried out by various scientists in developing resource provisioning model and their challenges in cloud computing environments and also compare the characteristics features of these resource scheduling algorithms. © International Science Press.