In software development and product management, a user story is one or more sentences in the everyday or business language of the end user or user of a system that captures what a user does or needs to do as part of his or her job function. User stories are used with agile software development methodologies as the basis for defining the functions a business system must provide, and to facilitate requirements management. It captures the 'who', 'what' and 'why' of a requirement in a simple, concise way, often limited in detail by what can be hand-written on a small paper notecard. User stories are written by or for the business user as that user's primary way to influence the functionality of the system being developed. User stories may also be written by developers to express non-functional requirements (security, performance, quality, etc.), though primarily it is the task of a product manager to ensure user stories are captured.
User stories are a quick way of handling customer requirements without having to create formalized requirement documents and without performing administrative tasks related to maintaining them. The intention of the user story is to be able to respond faster and with less overhead to rapidly changing real-world requirements.
A user story is an informal statement of the requirement as long as the correspondence of acceptance testing procedures is lacking. Before a user story is to be implemented, an appropriate acceptance procedure must be written by the customer to ensure by testing or otherwise whether the goals of the user story have been fulfilled. Some formalization finally happens when the developer accepts the user story and the acceptance procedure as a work specific order.
Creating user stories
When the time comes for creating user stories, one of the developers (or the product owner in Scrum (development) ) gets together with a customer representative. The customer has the responsibility for formulating the user stories. The developer may use a series of questions to get the customer going, such as asking about the desirability of some particular functionality, but must take care not to dominate the idea-creation process.
As the customer conceives the user stories, they are written down by the customer on a note card (e.g. 3x5 inches or 8x13 cm) with a name and a description which the customer has formulated. If the developer and customer find a user story deficient in some way (too large, complicated, imprecise), it is rewritten until it is satisfactory - often using the INVEST guidelines from the Scrum project-management framework. However, Extreme Programming (XP) emphasizes that user stories are not to be definite once they have been written down. Requirements tend to change during the development period, which the process handles by not carving them in stone.
- "As a <role>, I want <goal/desire> so that <benefit>"
- "As a <role>, I want <goal/desire>"
Chris Matts suggested that "hunting the value" was the first step in successfully delivering software, and proposed this alternative as part of Feature Injection:
- "In order to <receive benefit> as a <role>, I want <goal/desire>"
Another template based on the Five Ws specifies:
- "As <who> <when> <where>, I <what> because <why>."
The <what> portion of the user story should use either "need" or "want" to differentiate between stories that must be fulfilled for proper software operation versus stories that improve the operation, but are not critical for correct behavior.
- As a user, I want to search for my customers by their first and last names.
- As a non-administrative user,
- I want to modify my own schedules but not the schedules of other users.
- As a mobile application tester,
- I want to test my test cases and report results to my management.
- Starting Application
- The application begins by bringing up the last document the user was working with.
- As a user closing the application,
- I want to be prompted to save if I have made any change in my data since the last save.
- Closing Application
- Upon closing the application, the user is prompted to save (when ANYTHING has changed in data
- since the last save!).
- As a user closing the application,
- I want to be prompted to save anything that has changed since the last save
- so that I can preserve useful work and discard erroneous work.
- The consultant will enter expenses on an expense form.
- The consultant will enter items on the form like expense type,
- description, amount, and any comments regarding the expense.
- At any time the consultant can do any of the following options:
- (1) When the consultant has finished entering the expense,
- the consultant will “Submit”. If the expense is under fifty (<50),
- the expense will go directly to the system for processes.
- (2) In the event the consultant has not finished entering the
- expense, the consultant may want to “Save for later”. The
- entered data should then be displayed on a list (queue) for
- the consultant with the status of “Incomplete”.
- (3) In the event the consultant decides to clear the data and
- close the form, the consultant will “Cancel and exit”. The
- entered data will not be saved anywhere.
As a central part of many agile development methodologies, such as in XP's planning game, user stories define what has to be built in the software project. User stories are prioritized by the customer to indicate which are most important for the system and will be broken down in tasks and estimated by the developers.
When user stories are about to be implemented the developers should have the possibility to talk to the customer about it. The short stories may be difficult to interpret, may require some background knowledge or the requirements may have changed since the story was written.
Every user story must at some point have one or more acceptance tests attached, allowing the developer to test when the user story is done and also allowing the customer to validate it. Without a precise formulation of the requirements, prolonged nonconstructive arguments may arise when the product is to be delivered.
XP and other agile methodologies favor face-to-face communication over comprehensive documentation and quick adaptation to change instead of fixation on the problem. User stories achieve this by:
- Being very short. They represent small chunks of business value that can be implemented in a period of days to weeks.
- Allowing developer and the client representative to discuss requirements throughout the project lifetime.
- Needing very little maintenance.
- Only being considered at the time of use.
- Maintaining a close customer contact.
- Allowing projects to be broken into small increments.
- Being suited to projects where the requirements are volatile or poorly understood. Iterations of discovery drive the refinement process.
- Making it easier to estimate development effort.
- Require close customer contact throughout the project so that the most valued parts of the software get implemented.
A story map is the graphical, two-dimensional product backlog. At the top of the map are big user stories, which can sometimes be considered "epics” as Mike Cohn describes them and other times correspond to "themes" or "activities". These grouping units are created by orienting at the user’s workflow or "the order you'd explain the behavior of the system". Vertically, below the epics, the actual story cards are allocated and ordered by priority. The first horizontal row is a "walking skeleton" and below that represents increasing sophistication.
In this way it becomes possible to describe even big systems without losing the big picture.
Some of the limitations of user stories in agile methodologies:
- They can be difficult to scale to large projects.
- They are regarded as conversation starters.
User stories and use cases
While both user stories and use cases serve the purpose to capture specific user requirements in terms of interactions between the user and the system, there are major differences between them.
|User Stories||Use Cases|
- Acceptance testing
- Extreme Programming
- Use case
- Kanban board
- Agile software development
- INVEST mnemonic
- Daniel H. Steinberg and Daniel W. Palmer: Extreme Software Engineering, Pearson Education, Inc., ISBN 0-13-047381-2
- Mike Cohn, "User Stories Applied", 2004, Addison Wesley, ISBN 0-321-20568-5
- Mike Cohn: Agile Estimating and Planning, 2006, Prentice Hall, ISBN 0-13-147941-5
- Davies, Rachel. "Non-Functional Requirements: Do User Stories Really Help?". Retrieved 12 May 2011.
- Patton, Jeff. "The new user story backlog is a map". Retrieved 4 March 2013.
- Cockburn, Alistair. "Walking Skeleton". Retrieved 4 March 2013.
- "Story mapping". Agile Alliance. Retrieved 4 March 2013.
- Advantages of User Stories for Requirements