Polymorphic relationships in Laravel offer a streamlined approach to manage models that can belong to multiple other models, without creating redundant tables. By using polymorphic relationships, developers can create a single comments table that serves various entities like posts and pages, instead of separate tables for each. This is achieved through key columns such as `commentable_id` and `commentable_type`, which store the ID and class name of the related model, respectively. The article explains the implementation of one-to-one, one-of-many, and many-to-many polymorphic relationships, illustrating how entities like posts, pages, and products can share a common comments table. Examples include using polymorphic methods like `morphMany`, `morphTo`, and `morphOne` to define these relationships in Laravel models. Additionally, the text explores potential use cases such as managing user types, attachments, and media within applications, highlighting the benefits of polymorphic relationships in reducing database complexity and improving maintainability.