Azure Active Directory Business-to-Business (Azure AD B2B) is a feature of Microsoft Azure Active Directory that allows organizations to securely collaborate with external partners, suppliers, customers, or other businesses by providing controlled access to their applications and resources. Azure AD B2B simplifies the process of inviting external users to collaborate while maintaining security and compliance.

Here are some key aspects and features of Azure AD B2B:

1. Collaboration with External Users: Azure AD B2B enables organizations to invite external users who have email addresses from other domains to access their applications and resources. This can include granting access to Azure AD-secured apps, SharePoint sites, and other resources.

2. Invitation-Based Access: Organizations can invite external users to collaborate by sending them invitations via email. The invitations contain a secure link for the external users to accept, which initiates the process of granting them access.

3. Guest User Accounts: External users who accept invitations are referred to as “guest users.” They receive temporary, limited Azure AD accounts that are managed by the inviting organization. These guest accounts are separate from the user’s home organization and can be removed or revoked by the inviting organization at any time.

4. Authentication and Authorization: Azure AD B2B provides authentication and authorization mechanisms to ensure that guest users can only access the resources they have been granted permission to access. This is achieved through role-based access control (RBAC) and conditional access policies.

5. Single Sign-On (SSO): Guest users can benefit from single sign-on capabilities, allowing them to use their existing credentials to access the resources they have been invited to without the need for additional usernames and passwords.

6. Multi-Organization Collaboration: Azure AD B2B supports collaboration between multiple organizations, making it suitable for scenarios where multiple businesses need to work together while maintaining a degree of isolation and control.

7. Self-Service Signup: Organizations can configure Azure AD B2B to allow external users to sign up for access using their email addresses, subject to approval and verification by the inviting organization.

8. API Access: Guest users can be granted access to APIs and web services secured by Azure AD, facilitating programmatic collaboration between organizations.

9. Security and Compliance: Azure AD B2B incorporates security features such as multi-factor authentication (MFA), conditional access policies, and identity protection to ensure secure collaboration. It is also compliant with various industry standards and regulations.

10. Logging and Auditing: Organizations can monitor and audit guest user activities within their environment, helping to ensure compliance and security.