There is a need to relate two entities in the data structure: Employee and Skill.

 A many-to-many relationship is a type of relationship where multiple records in one table are associated with multiple records in another table. To implement a many-to-many relationship, a third table is needed to store the associations between the two entities. In this case, the third table would store the employee ID and the skill ID for each pair of employee and skill. This design allows for efficient querying and updating of the data, as well as avoiding data redundancy and inconsistency.