A Scrum Team is required to deliver a done Increment by the end of a...

 A Scrum Team is required to deliver a done Increment by the end of a Sprint. Done means:

No work is left to meet the Definition of Done. The Definition of Done is a formal description of the state of the Increment when it meets the quality measures required for the product. It is a shared understanding among the Scrum Team and the stakeholders of what it means for work to be complete. It may include criteria such as coding standards, testing, documentation, security, performance, etc. If a Product Backlog item or an Increment does not meet the Definition of Done, it cannot be released or presented at the Sprint Review.

Ready to be released to end users. The Increment is a concrete output of the Sprint that adds value to the product. It is a potentially releasable functionality that adheres to the Scrum Team’s current Definition of Done. It is not necessarily released at the end of each Sprint, but it must be in a state that allows for immediate release if the Product Owner decides so. The Increment should also align with the Sprint Goal and the Product Goal, and satisfy the needs and expectations of the customers and stakeholders.