requirements document itself becomes a goal. A requirements document should be written only when it helps achieve the real goal of delivering some software.
alliteration of Card, Conversation, and Confirmation (Jeffries 2001). The Card may be the most visible manifestation of a user story, but it is not the most important. Rachel Davies (2001) has said that cards "represent customer requirements rather than document them." This is the perfect way to think about user stories: While the card may contain the text of the story, the details are worked out in the Conversation and recorded in the Confirmation.
Independent Negotiable Valuable to users or customers Estimatable Small Testable
Stories must be written so as to be testable. Successfully passing its tests proves that a story has been successfully developed. If the story cannot be tested, how can the developers know when they have finished coding?