Muhammad Rahmani - Doctorate in Information Technology Engineering,University of tehran
Fariba Noori - Ph.D. in Linguistics,Department of Linguistics, Faculty of Humanities, Tarbiat Modares University,Tehran,Iran
Alireza Esmaeili Jobani - Master's student in computer engineering,istanbul Aydin Universitesity

Organizations use cloud computing in many service models such as (software as a service, infrastructure as a service and platform as a service) and extended models such as (private, public and hybrid). There are security issues and concerns related to cloud computing, but all these concerns are divided into ۲ general categories: first, security issues related to cloud computing providers and second, security issues related to customers. In most cases, the provider must be sure that its infrastructure is secure and protect its customers' data and applications, while the customer must be sure of the performance of the cloud computing service provider in order to establish appropriate security measures to protect its data. The widespread use of virtualization in the implementation of cloud computing infrastructure has created security concerns for both customers and public cloud computing services. Today, cloud computing is one of the latest topics in the world of information technology, and security in cloud computing is considered one of its most important parts. Cloud security or information security in cloud computing is a set of policies, checks, methods and technologies used together to protect cloud applications, systems, data and information. Today, with the increasing development of technology and the demand for network-based services, the need for a platform to perform extra-organizational calculations and processing becomes more colorful. On the other hand, the cost of creating internal data centers drives companies (even some large companies) to use third-party data centers. But the most important challenge for these companies to use these services is the issue of security. In this article, we will first give a brief explanation about the cloud and then present the main concepts and challenges of cloud computing security

cloud computing, security, virtual machine