What feature in Sitefinity allows for establishing a reusable design layout?

The feature in Sitefinity that enables the creation of a reusable design layout is the Page Template. Page Templates serve as a foundational structure for how content is displayed across multiple pages within a website. They allow developers and content editors to define specific design elements, including layout, widgets, and styling, which can then be consistently applied to various pages to maintain a uniform look and feel.

By utilizing Page Templates, organizations can streamline their design process, ensuring that updates to the layout or style can be made centrally within the template. This not only saves time but also upholds a cohesive branding strategy throughout the site. Furthermore, as modifications are made to a Page Template, all associated pages automatically reflect those changes, enhancing the efficiency of site management.

The other options do not provide reusable design layouts in the same way. Custom Widgets are designed for specific functions and can be reused but do not define layout directly. The Site Map Tool primarily focuses on visualizing site structure rather than layout design. The User Interface Module relates to broader design elements but does not encapsulate the concept of reusable layouts as clearly as Page Templates do.