Active Directory uses a hierarchical, domain-based structure, where each domain represents a logical grouping of network resources and users. Within each domain, there are a number of different types of objects that can be stored, such as:

• User objects: which represent individual users on the network, and contain information such as the user's name, password, and group memberships.
• Computer objects: which represent the computers on the network, and contain information such as the computer's name, IP address, and operating system version.
• Group objects: which represent collections of users or computers, and can be used to manage access to network resources.
• Organizational Unit (OU): which are a container for other objects, such as users and computers. it is used to organize the AD domain in a logical way.

Active Directory provides a number of services such as:

• Authentication: which is used to verify a user's identity and grant access to network resources.
• Authorization: which is used to determine what resources a user is allowed to access, based on their group memberships and other attributes.
• Group Policy: which is used to control the configuration and settings of computers and users in the domain.
• Domain Name System (DNS): which is used to translate domain names to IP addresses.

Active Directory can also be integrated with other Microsoft technologies such as Exchange, SharePoint, and Skype for Business. In addition, Active Directory can be integrated with non-Microsoft software and systems, via LDAP (Lightweight Directory Access Protocol) or other means, which allows AD to connect with third-party applications and network devices.

Active Directory is an important part of a network infrastructure and plays a vital role in managing user identities and access to network resources. It can help to ensure security and compliance, automate repetitive tasks, and improve overall IT management and support.