When talking about requirements, SMART refers to the following qualities:
Specific requirements are ones that pair a vague feature (e.g. The user can search for a movie) with a specific qualifier (e.g. by its title).
Making a requirement measurable ensures that it is testable. For instance, we may have a requirement that an end-to-end response time for a feature should be less than 3 seconds.
Achievable requirements are those that can be completed in a single sprint or iteration. Larger requirements can be made achievable by breaking them into smaller components.
A requirement is relevant when it has business value to stakeholders. In order to drill down to what is most important for stakeholders, asking the “Five Whys” is key.
Development on a requirement is timeboxed–all work stops at the end of the sprint. If the requirement was unachievable, the remaining work can be rescheduled as a new story. If necessary, the requirement can be further broken down into smaller requirements that are attainable. It is also possible to scrap the requirement.
Crafting good requirements or user stories means adhering to these SMART guidelines.