Foundations: Because it contains a description of its own structure (schema, table/column definitions, constraints), a database is considered to be ________.

Introduction / Context:
A hallmark of database systems is that they store not only data, but also metadata that describes that data. This architectural property underpins tools, catalogs, and portability.

Given Data / Assumptions:

• Relational systems maintain catalogs (information schema, system tables).
• The question points to the database storing and exposing its own structural description.

Concept / Approach:
“Self-describing” means that the system keeps its schema and object definitions inside the database itself, accessible through system catalogs or information schemas. Applications and admins can query these catalogs to discover structure programmatically.

Step-by-Step Solution:

Verification / Alternative check:
Standards like ISO SQL define INFORMATION_SCHEMA; popular DBMSs expose system catalogs that applications can query.

Why Other Options Are Wrong:
Described / metadata compatible: Vague terms, not standard DBMS terminology.
An application program: A database is a data store, not an application.

Common Pitfalls:
Confusing database engines with applications; conflating data with schema without recognizing metadata access.

Final Answer:
self-describing