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.
TLDR:
Authentication confirms who a user is; authorization decides what that verified user can do. They always run in sequence.
Enforcing MFA cuts credential-theft risk nearly in half, per the 2025 Verizon DBIR.
Disabling an IdP account does not fully revoke access. Apps keep sessions alive through their own tokens until removed app by app.
AI agents need their own verified machine identities and scoped permissions, not borrowed human credentials.
AccessOwl sits in the authorization layer as a governance tool, not an authentication provider. Your IdP still handles MFA and SSO.
Where authentication and authorization stand in 2026
Identity has become the primary attack surface for most organizations, and access controls have shifted accordingly. Passwords are being replaced by phishing-resistant passkeys, which are now backed by every major operating system and browser. Zero trust has moved from a buzzword to a default expectation: every request is verified, and access is granted per session based on context. On the authorization side, teams are moving away from static, role-only models toward attribute- and policy-based decisions that account for device health, location, and risk signals. For security and IT teams, the practical takeaway is that authentication and authorization can no longer be treated as one-time gates. They are continuous, context-aware checks that run throughout a user's session.
Authentication and authorization for AI agents
A newer wrinkle is non-human identity. AI assistants, copilots, and autonomous agents now call APIs and act on a user's behalf, so each one needs its own verified identity and its own scoped permissions. The same two questions still apply: who is this agent (authentication), and what is it allowed to do (authorization)? Best practice is to give every agent a distinct machine identity, grant it least-privilege access through scoped tokens rather than a human's full credentials, and log its actions for audit. Treating agents as first-class identities keeps AI-driven access inside the same zero trust controls you already apply to people.
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 sets 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. Teams that grant access at scale often lean on access request automation tools to keep these decisions consistent. 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 let employees work productively and securely. Both processes serve to safeguard data integrity and confidentiality while keeping day-to-day work running smoothly.
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)
Strong security combines multiple authentication methods. This often includes a code from a mobile authenticator app or a hardware key. Passkeys have now become a widely adopted option, a phishing-resistant credential supported by the FIDO Alliance passkeys. A passkey stores a private key on the user’s device and uses biometrics to unlock it.
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 day-to-day 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, finalized in 2025, 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.
Model | Description |
|---|---|
RBAC | Access rights based on job roles |
ABAC | Access determined by multiple attributes |
ACL | Per-user permissions list |
DAC | Access decided by the resource owner |
MAC | Central authority determines access |
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.” For audited teams, mapping these controls to a framework is easier with access management tools for SOC 2 compliance. When least-privilege rights are enforced, security risks are reduced and regulatory compliance is met.
Authentication vs. SSO vs. access management vs. identity governance
IT and security teams often ask how these related terms fit together, because vendors use them loosely. Authentication answers who a user is. Single sign-on (SSO) is one way to handle authentication across many apps from a single login. Access management decides what an authenticated user can reach and provisions or removes that access. Identity governance sits above all of it, giving you the audit trail, access reviews, and least-privilege controls that prove the right people have the right access over time.
A common follow-up: why isn't suspending someone's identity provider account enough to cut off access? Because many apps keep a user's session alive through their own tokens, and apps a user signed up for outside the IdP were never tied to it in the first place. Fully revoking access means removing the account inside each connected app, not just disabling the central login.
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. Once consent is received, an access token is generated, which provides access rights to the application or website.
FAQ
What is the difference between authentication and authorization?
Authentication verifies who a user is, confirming their identity before granting access. Authorization determines what that verified user can actually do, such as reading a file, editing a document, or accessing a specific system. The two always work in sequence: authentication runs first, authorization follows.
Why isn't disabling someone's identity provider account enough to fully remove their access?
Suspending an IdP account leaves session tokens alive inside individual SaaS applications. Slack, for example, keeps sessions active regardless of IdP status, meaning a suspended user can stay logged in for hours or days. Complete offboarding requires disabling the account inside each connected application, not just at the IdP layer.
RBAC vs. ABAC: which authorization model should I use for a 50 to 200 person company?
RBAC (Role-Based Access Control) is faster to set up and works well when job roles map cleanly to access needs, making it the practical starting point for most lean teams. ABAC (Attribute-Based Access Control) gives you finer control by layering in attributes like department, location, or device health, but it requires more configuration overhead to maintain. Start with RBAC, then add attribute-based conditions once your access policy needs outgrow simple role assignments.
How do OAuth 2.0, SAML, and SCIM fit together in an IAM setup?
They solve different problems in the same stack. SAML handles cross-domain single sign-on, letting users authenticate once across federated enterprise applications. OAuth 2.0 and its identity layer, OIDC (OpenID Connect), manage delegated authorization, controlling what third-party apps can access on a user's behalf. SCIM (System for Cross-domain Identity Management) is a separate provisioning protocol that automates account creation and removal across applications, and it is the layer most frequently gated behind enterprise-tier SaaS plans.
What does "zero trust" actually require from authentication and authorization in practice?
Zero trust means neither authentication nor authorization is treated as a one-time gate: every request is verified based on current context, including device health, location, and risk signals. In practice, this means implementing MFA (Multi-Factor Authentication) with phishing-resistant options like passkeys, applying step-up authentication when risk signals change, and granting access per session instead of assuming a previously authenticated user remains trustworthy throughout their session.