What is the purpose of user stories in a product backlog?

User stories in a product backlog serve the purpose of prioritizing features from a user perspective. They are short, simple descriptions of a feature told from the perspective of the end-user. User stories help to capture the desired functionality, who needs it, and why. By focusing on the user's needs, user stories ensure that development efforts are aligned with delivering value to the customer. They also facilitate communication and collaboration between stakeholders and the development team, ensuring a shared understanding of requirements.