A new element mapper is provided for mapping elements of a page using user-provided or automatically generated terms or names. Specifically, a user may direct an application displaying a page to enter into an in-context element mapping mode, in which page elements eligible for mapping may be identified and highlighted whenever one is moused or hovered over. Responsive to the user selecting a page element of interest, the element mapper may provide a dialog with an input field. The dialog may be displayed near the page element of interest or as part of the page. Based on a user-provided or automatically generated name, the element mapper may generate a mapping output and store it in association with a selector for the page element of interest. The mapping output can be used to build a site rule in context of the page element of interest.