In ServiceNow, extending a table means creating a new table (child class) that inherits properties from an existing table (parent class). This inheritance includes fields, business logic, and other configurations, allowing for efficient reuse and customization.

Key Points:

Field Inheritance: The child table inherits all fields from the parent table. For example, if you extend the Task table, your new table will include fields like "short_description" and "priority."

Business Logic Inheritance: The child table also inherits business rules, client scripts, and other logic defined on the parent table, ensuring consistent behavior across related tables.

Access Controls: Access controls are not ignored; instead, the child table inherits the parent table's access controls. However, you can define additional access controls specific to the child table as needed.

Customization: While the child table inherits many properties, you can add new fields, scripts, and behaviors to tailor it to specific requirements without affecting the parent table.