According to the Scrum Guide1, the definition of "Done" is a formal description of the state of the Increment when it meets the quality measures required for the product. The definition guides the Development Team in creating a "Done" Increment. The definition of "Done" is created by the development organization (or Development Team if none is available from the development organization). The definition of "Done" may vary significantly per Scrum Team, depending on the context. One aspect of Scrum Teams inspecting how they work toward their Product Goal is that they improve their definition of "Done" over time. Therefore, one good way for a Scrum Team to ensure security concerns are satisfied is to add security concerns to the definition of "Done". Another good way is to have the Scrum Team create Product Backlog items for each concern, as they are responsible for managing and refining the Product Backlog.

According to the Scrum Guide1, an Increment is a concrete stepping stone toward the Product Goal. Each Increment is additive to all prior Increments and thoroughly verified, ensuring that all Increments work together. In order to provide value, an Increment must be usable. Multiple Increments may be created within a Sprint. The sum of the Increments is presented at the Sprint Review thus supporting empiricism. However, an Increment may be delivered to stakeholders prior to the end of the Sprint. The Sprint Review should never be considered a gate to releasing value. Therefore, in order to turn Product Backlog items into an Increment of potentially releasable product functionality, the Development Team should have all the skills needed.

https://scrumguides.org/docs/scrumguide/v2020/2020-Scrum-Guide-US.pdf
Scrum is a framework for developing, delivering, and sustaining complex products. Scrum has three roles: the Product Owner, the Scrum Master, and the Developers. The Developers are the people in the Scrum Team who are committed to creating any aspect of a usable Increment in each Sprint. The Developers are not limited by titles such as programmer, designer, tester, architect, engineer, etc. The Developers are responsible for all aspects of quality, including finding and fixing bugs, tracking quality metrics, and verifying the work of other Developers. Therefore, Scrum has no "tester" role, and the Developers are responsible for quality.

According to the Scrum Guide1, each event in Scrum is a formal opportunity to inspect and adapt something. These events are specifically designed to enable critical transparency and inspection. Failure to include any of these events results in reduced transparency and is a lost opportunity to inspect and adapt. All events are time-boxed events, such that every event has a maximum duration. Once a Sprint begins, its duration is fixed and cannot be shortened or lengthened. The remaining events may end whenever the purpose of the event is achieved, ensuring an appropriate amount of time is spent without allowing waste in the process. The time-box for the Daily Scrum is 15 minutes or less for a one-month Sprint. Its location and time remain constant.