The document discusses principles for maintaining application state when users return to an app or website. It argues that applications should represent the last view or state the user was in previously rather than defaulting to a main settings or home page. Examples are given of apps like Chrome and Instapaper that successfully retain the last state when reopened, providing better user experience than those that do not preserve the user's context between sessions. Constraints to consider include device memory and usability, but the benefits of reducing user frustration outweigh the costs.