The properties you can set in a site configuration are determined by the modules that are running and the site category you choose to base your site on. In other words, the ATG platform includes a set of properties, Commerce includes additional properties, other ATG products include still more, and you may also have custom properties defined for your sites. Correspondingly, the site category you choose may show some properties, hide others, and define property behavior such as defaults and the editors you use to set them. You edit site properties in Site Administration. For detailed instructions on using Site Administration, see Defining Site Categories.