User Story

A User Story is a story told by the user (of the product) of her/his challenges, or opportunities.

The original intent of the User Story has been that a User Story is to be told not written.

A User Story card is a promise for further communication. Communication that should happen between the Developers and the Customer or Stakeholders to create a shared understanding of the user's needs.

Further Reading:

Writing Effective User Stories Becoming User Centric with User Stories

Also see:

Product Backlog Item, Spike, Technical Debt, Splitting User Stories