Authentication and authorization are core pillars of IAM (identity and access management). These two terms are often used interchangeably; however, they have different but complementary roles. As cybersecurity threats become more sophisticated, organizations must implement strong identity-based controls to protect sensitive data and systems.

This article explains what authentication and authorization are, how they work together, and why both are critical for modern digital security.

What are authentication and authorization?

Simply put, user authentication verifies that a user is who they say they are, and authorization determines what they can (or can’t) access once they’re authenticated. When a user attempts to access a resource, the system first authenticates the user’s identity and then checks the access rights during the authorization phase. Authorization follows successful authentication. Authentication is the gateway to any secure system, while authorization dictates the boundaries within that system.

What is the purpose of authentication?

The authentication process verifies that a person is who they say they are. Once they’re verified, access is allowed. Access control is vital to the security of apps, devices, files, and data. Authentication applies to both people and devices. Enforcing authentication ensures that unauthorized access is prevented and minimizes the risk of data breaches, insider threats, and account takeovers.

What is the purpose of authorization?

After a user or device has been authenticated, the type of access needs to be decided. This is known as authorization. An authorization decision may be based on an individual or a role. Access privileges will restrict access to certain network areas and determine what actions are allowed after access. Authorization is an essential component of privileged access management (PAM) and compliance frameworks such as GDPR and HIPAA.

Similarities between authentication and authorization

Authentication and authorization are complementary. Authorization occurs after a successful authentication event. Authentication and authorization work together to protect corporate resources. Together, these controls ensure that employees can work productively and securely. Both processes serve to safeguard data integrity and confidentiality while ensuring operational efficiency.

Which comes first, authentication or authorization?

A person (or device) supplies the login credentials. If the login is successful, authorization is next. An authorization scheme decides what the user can do with the resource. For example, the user may be able to access an app but not edit documents. Authorization reduces data breaches and leaks. In today’s zero trust environments, this sequence is critical for limiting lateral movement across networks.

Common types of authentication

Username and password combos are a form of single-factor authentication. However, phishing and spear phishing have made passwords highly vulnerable. To resolve this, different types of user credentials have been developed. Authentication can be split into three main categories:

• Something you know, such as a password. Other similar methods include security questions and one-time PINs that work for a single session.

• Something you possess is usually a mobile device, app, or a digital ID card, or even something like a boarding pass.

• Something you are can be a biometric — this includes facial recognition and fingerprints.

The use of multiple authentication factors (multi-factor authentication) provides stronger protection against modern cyber threats.

Multifactor authentication (MFA)

Robust security combines multiple authentication methods. This often includes a code from a mobile authenticator app or a hardware key. A newer option in 2025 is the passkey, a phishing-resistant credential supported by the FIDO Alliance. It stores a private key on the user’s device and uses biometrics to unlock it. A recent survey found that two-thirds of users familiar with passkeys prefer them for daily logins.

Using MFA reduces the chance of successful phishing based on single-factor security. According to the 2025 Verizon DBIR, organizations that enforced MFA on user accounts saw the likelihood of credential-theft incidents cut nearly in half. Multiple authentication factors reduce the risk of cyberattack and accidental data exposure. MFA is a best practice access control measure. Two factors of authentication are known as two-factor authentication (2FA).

Key Benefits of MFA

• Blocks the majority of credential-based cyberattacks

• Improves regulatory compliance and audit readiness

• Increases user trust and confidence

• Reduces operational risks and IT helpdesk requests

Requiring additional credentials for resource access makes it harder for hackers to access data and resources. Strong authentication is a must-have to reduce successful phishing attacks.

Risk-based authentication

Rules add more security to the user authentication process, This is known as risk-based authentication, step-up authentication, or risk-based access control. For example, a rule could require further authentication factors if a user logs in outside the corporate firewall.

NIST SP 800-63-4 formally encourages step-up flows when risk signals change, empowering organizations to customize their access policies based on contextual data.

Single-Sign-On (SSO)

SSO is an authentication scheme. SSO allows employees to sign in once to access multiple federated apps securely. SSO schemes are based on federated identity.

SSO is frequently implemented in large enterprises, SaaS ecosystems, and academic institutions.

Common types of authorization systems

There are many authorization mechanisms. The types of authorization process you can choose from include:

Role-based access control (RBAC): Access permissions and privileges are set according to specific roles in an organization. For example, accounts payable employees may be allowed full edit access to accounting software, whereas HR staff may have read-only access. Sensitive data is protected using least-rights privileges to apps and files while ensuring uninterrupted access for work.

Attribute-based access control (ABAC): Uses attributes to set access privileges and access restrictions. These attributes are based on:

• The subject

• Environment

• Action

• The objects

Access control list (ACL): An ACL is a list of access permissions assigned on a per-user basis. ACLs prevent unauthorized users from accessing corporate resources. ACLs authorize access to files, directories, apps, or the network. An ACL can allocate user read and write privileges.

Other types of authorization methods include Discretionary Access Control (DAC), a form of distributed, resource owner-controlled authorization, and Mandatory Access Control (MAC), which is based on security labels.

Protocols and standards used in authentication and authorization

Authentication protocols and authorization protocols are an essential part of an IAM system:

SAML (Security Assertion Markup Language)

SAML is an open federation standard that became an OASIS standard in November 2002. SAML 2.0 is the latest version. Many IdPs continue to use SAML, including enterprise applications and government online services. SAML is used for cross-domain SSO.

Open Authorization (OAuth) 2.0

OAuth is a framework that allows a person to authorize access to digital resources without revealing their identity. For example, federated social login systems such as Google and Facebook use OAuth federation to provide access to third-party websites.

OpenID Connect (OIDC)

OIDC is an identity authentication protocol. OIDC is built on the OAuth 2.0 protocol. OIDC was released in 2014, but mass uptake took several years. OIDC is now used across the internet to authenticate and authorize users. OIDC creates an access token and ID token when users sign in, to control user access.

System for Cross-domain Identity Management (SCIM)

SCIM is an HTTP-based protocol that standardizes identity exchange across multiple domains. Uses offered by the Internet Engineering Task Force (IETF) community, which developed the protocol, include enterprise-to-cloud service providers and inter-cloud scenarios.

Why authorization is important for security and automation

Security and usability have always been two sides of a balancing act. However, an automated authorization scheme can maintain this balance. Authorization systems provide the critical components of enterprise cybersecurity: orchestration and automation of access rights privileges. While authentication controls access, authorization controls privilege. Organizations can set privileges and permissions based on a predefined role or individual level, using the principle of least privilege. NIST defines least privilege as “the principle that a security architecture is designed so that each entity is granted the minimum system resources and authorizations that the entity needs to perform its function.” When least-privilege rights are enforced, security risks are reduced and regulatory compliance is met.

How Google handles authentication and authorization through Sign in with Google

Google SSO can be used to sign in to all Google Workspace apps using a single login (SSO) session. This same SSO service can also be used for other non-Google web apps or websites. Apps or websites that use Sign in with Google allow Google to handle their identity management. Whenever a user attempts a log in to the integrated app or website, an authentication request is sent to Google’s authentication service. On login, a user is asked to enter their Sign-in credentials. If this is the first time they’ve used Google to sign in to this app or website, the user will see an OAuth consent screen. This screen allows the user to grant permission to share data, such as their email address. Once consent is received, an access token is generated, which provides access rights to the application or website.