In SQL, the set of commands used for defining database schema objects (such as CREATE, ALTER, and DROP) make up which language category?

Introduction / Context:
SQL statements can be classified based on their purpose. Data Definition Language (DDL) refers specifically to schema-level commands, which are critical for designing and maintaining database structures.

Given Data / Assumptions:

• DDL includes CREATE, ALTER, DROP, TRUNCATE.
• The question focuses on commands that define data structures.

Concept / Approach:
DDL commands manage schema-level objects: tables, indexes, views. These operations change metadata and require commit/rollback handling depending on DBMS implementation.

Step-by-Step Solution:

Verification / Alternative check:
Database manuals group CREATE TABLE and DROP TABLE under DDL, distinct from data manipulation (DML).

Why Other Options Are Wrong:
DML: Affects data, not structure.
HTML/XML: Document markup, unrelated to SQL schema definition.

Common Pitfalls:
Confusing DDL with DML; remember DDL defines structure, DML manipulates data inside structures.

Final Answer:
DDL