As mentioned in Chapter 4, some attributes of SVG elements control the element’s geometry. An example of one such attribute would be the cx (center x) attribute of a <circle>. Other attributes, such as fill, control the element’s presentation. Stylesheets provide a way for you to separate the presentation from the geometric structure; this lets you control the visual display of many different SVG elements (and even documents) by changing one stylesheet referenced by all the documents.