Tenant in Microsoft Azure cloud service works as an organization and created in Azure Active Directory. In Azure Active Directory all the users and applications are into a group, and these groups are known as tenants. An app developer receives tenant as a dedicated instance of Azure Active Directory to create a connection with Microsoft cloud service. This tenant id can be used for sign-in credentials to Azure, Microsoft 365 or Microsoft Intune etc.

On Microsoft identity platform to build an app for identity and access management, user need to access an Azure Active Directory (Azure AD) tenant. Basically Azure tenant is a directory, and the subscription is an object that represents a "folder". A tenant can have multiple subscriptions.

Every Azure AD tenant is separate from other Azure AD tenants. Each has its own representation of work and school identities (Azure AD), consumer identities (Azure AD B2C tenant), and app registrations. 

• Azure AD: Work and school (Azure AD) accounts or Microsoft accounts (example: Outlook.com and Live.com).
• B2C: Social and local (Azure AD B2C) accounts.
• App registrations: Inside tenant it can allow authentications only from accounts within tenant or all tenants. 

Advantages:

• A tenant can be associated with multiple subscriptions.
• Allow access to include Microsoft Office 365, Dynamic 365 and Azure Intune.
• Authentication standard (Web-based).
• Easy to create.
• More secure.
• User can create single or multi-tenant as needed.