Cardinality question: in which relationship type can many instances of one entity be related to many instances of another entity?

Introduction / Context:
Many-to-many (M:N) relationships are common in domains such as course enrollments or product orders. Recognizing them is key because their relational implementation requires an associative (junction) table.

Given Data / Assumptions:

• Each entity on the first side can be associated with many on the second side.
• Each entity on the second side can also be associated with many on the first side.

Concept / Approach:
An M:N relationship connects multiple instances on both sides. In relational databases, you implement it by introducing a third table whose foreign keys point to each parent; together they can form the primary key or a unique constraint.

Step-by-Step Solution:

Verification / Alternative check:
Examples: Students and Courses; Tags and Articles; Doctors and Patients (in some contexts).

Why Other Options Are Wrong:

• One-to-one and one-to-many do not allow many associations on both sides.
• Composite relationship is not the standard cardinality label here.

Common Pitfalls:
Attempting to represent M:N with foreign keys in just two tables; this design leads to duplication or nulls. Use a junction table instead.

Final Answer:
Many-to-Many Relationship