In computer-speak, a user interface (abbreviated UI) is the means by which a program communicates with its user. It includes graphics, by which the program displays important aspects of its internal state to a user, and also mouse and keyboard actions, by which the user commmunicates to the program. This page describes Europa Universalis II's user interface. Note that all articles at the wiki that relate to the EU2 user interface should be tagged with the Europa Universalis II user interface category, as is this article. You can select the link there to see all the pages in the category.