In present authentication systems on the web, users are compelled to interact with identity providers. Initially, they are required to register on a particular website wherein they fill all their details. After this stage, they get a user id and password or token which they can use for accessing the application and their respective features. However, from security point of view, this type of system can be challenging. In such systems, authentication of data is available with the identity providers. It could be hacked to obtain the user passwords and other details. Various current systems track the activity of users and users provide access to sensitive information for the same. For example, access to storage, files, contacts, etc. To make sure that data is available, third-party servers are required which need to be available during authentication. In current, various methods for authentication such as Single-Factor, Two-Factor Authentication (2FA), Single Sign-On, Multi-Factor Authentication, etc are used. In this paper, we will study the authentication systems, their advantages and flaws along with the protocols used.