Cloud computing is an internet-based computing, where a set of resources and services such as applications, storage, and servers are delivered to computers and devices through the Internet. Cloud Computing is continuously growing and showing consistent growth in the field of computing. The major challenging task in cloud computing is the security and privacy issues caused by the outsourcing of infrastructure, sensitive data and critical applications and its multi-tenancy nature. The security for Cloud Computing is emerging area for research work and this paper discusses various types of authentication methods.