Knowledge is one of the factors that affect the size of a story. It refers to what is known or unknown about the story, such as the requirements, the design, the technology, the domain, the dependencies, and the risks. The more unknowns there are, the larger the story size will be, as it will require more effort, complexity, and uncertainty to implement. Knowledge is one of the components of the story point estimation technique, which is a relative measure of the effort required to implement a story. Story points take into account the volume, complexity, knowledge, and uncertainty of the work. References: Story - Scaled Agile Framework, Story Point - Scaled Agile Framework, How to Estimate Agile Stories: Introducing Relative Sizing - LeanDog, Estimate Story - Quickscrum, Agile Estimation – Feature and Story Sizing Scales