Any resource that is present within an Active Directory.
Attributes
Every object has an associated set of attributes that define the characteristics of that object, e.g. a computer has a Host name and DNS name.
Every attribute has an associated LDAP name, that can be used for LDAP queries.
sID History
Holds any Windows Security Identifier (SID) that an Object has previously been assigned to. It is usually used in migrations so a user can maintain the same level of accessed when moved to another Domain.
If this attribute is set insecurely an attacker can abuse it to gain prior elevated access that an account had before a migration if SID is not enabled.