element classification definition

Elements can be classified into two main CSS groups; these two groups are replaced and non-replaced.  Elements can differ substantially in how they are presented depending on which group they belong to.  Most HTML and XHTML elements belong to the nonreplaced group; in this group, an element’s content is viewed by the user agent within a box created by the element itself.   Most elements in HTML and XHTML are nonreplaced elements, such as paragraphs, lists, table cells and headings.