Confidentiality and security to the data is actually provided by an authentication. Authentication involves the confident identification of one party by another party or a process of confirming an identity. But now-a-days there are various methods for authentication such as message authentication code, signcryption, and key aggregate system are emerged very rapidly for better security precaution. This paper tries to investigate how to provide authentication in wireless sensor networks. Other goals are to give an introduction to general security in wireless sensor networks. As wireless sensor networks are the point of attention of numerous researchers regarding the security issue in the past several years.