What Is Authentication?

Written by Coursera Staff • Updated on

Learn about authentication, its purpose, and how it identifies users for a server or client.

[Featured image] A learner is researching about authentication on their laptop.

Authentication is a security process that ensures only users with permission can access information, systems, or other resources to guard against fraudulent activity or security breaches. The process requires that your credentials match those stored in a system; you may not gain access if they don’t match. 

You can use authentication to know and screen users who access and view your website and keep unauthorized users from gaining entry or access. When you require authentication, you ensure and protect the integrity of the files or site. Read on to learn about the different types of authentication and how companies use them. 

Read more: Information Technology (IT) Terms: A to Z Glossary

Types of authentication 

Organizations rely on different types of authentication to keep resources and sites safe and secure from cybercrime and other security breaches. Users provide one (or more) of three primary forms of authentication: Something you know, have, or are. 

A password or PIN offers a prime example of something you know, while something you have can come from a special code that’s sent to your phone or email. Facial recognition and fingerprints provide proof of who you are. Some organizations may use only one type of authentication or a combination of these methods depending on the desired level of security that an organization requires. 

  • Single-factor authentication: Also referred to as password-based authentication, single-factor authentication is commonly used and provides the lowest protection in terms of security. With this type of authentication, you input a password to gain access. 

  • Two-factor authentication: You must input two of the three categories of authentication. For example, in addition to a password, users may also have to answer a security question, enter a one-time passcode, or provide a code sent via email or SMS. 

  • Multifactor authentication: It’s considered a multifactor authentication process when it requires three or more steps. Multifactor authentication requires users to provide various means of proving their identity. 

  • Token-based authentication: Token-based authentication is a form of two-factor authentication that requires users to provide either a physical or digital token to prove their identity and gain access. The token is typically a computer-generated code based on encryption and serves as the user’s digital signature. An example of token-based authentication is a one-time code or password. The validity of the one-time code typically has only a short window of time for use. 

  • Certificate-based authentication (CBA): Relying on a digital certificate to verify identity, this type of authentication requires something that the user has and what the user knows. The user signs a piece of randomly generated data. The user then sends that signed piece of data and the digital certificate for authentication through the server’s network. Some organizations prefer the certificate-based method because it requires something you have (the private key) and something you know (the password protecting the key). You’ll often find CBA in use when users want to access an intranet server, corporate email, or certain cloud-based apps. 

  • Biometric authentication: Biometric authentication requires you to use a part of your own body, like your fingerprint, your voice, your face, or your eyes, to gain access. As a commonly used method for two-factor authentication, biometric authentication is more secure than other methods since it requires you to provide something completely unique to yourself. Facial recognition software used to unlock a smartphone is an example of biometric authentication at work. 

Next steps 

Learn more about the authentication process as you prepare for a career in IT support. Consider the Google IT Support Professional Certificate, offered on Coursera, to gain the skills and knowledge you’ll need to pursue a career in the field of IT. Upon completion, gain a shareable Professional Certificate to include in your resume or LinkedIn profile. 

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