In agile software development, a user story is a brief, simple description of a software feature from the perspective of an end user. It typically follows the format: "As a [type of user], I want [a goal] so that [reason]." User stories facilitate clear communication among team members and help prioritize the development process based on user needs. They serve as a foundation for defining acceptance criteria and guiding development efforts. By focusing on user-centric features, user stories enhance the overall application effectiveness and align development with business objectives. This practice encourages collaboration and adaptability within agile teams, ultimately leading to improved software quality.