In the Agile world, user stories are statements of intent that describe the application functionality – things that the system will do for the user. They are analogous to software requirement statements.
The planning process, user stories are sized and placed into the appropriate iteration. Estimating stories points is similar to estimating how long it takes to deliver the value the story represents to the customer. A story point is a positive integer representing the combination of various aspects, such as:
- knowledge: does the individual or team know what is asked by the story?
- complexity: how hard is implementation?
- volume: how big is it, how long should it take to complete?
- uncertainty: what are the unknowns?
The most common method to estimate story points is the relative estimation. It combines the dimensions above into a number that is then compared to the size of stories of similar size.