Each taxonomy term (often called a 'category' or 'tag' in other systems) automatically provides lists of posts and a corresponding RSS feed. These taxonomy/term URLs can be manipulated to generate AND and OR lists of posts classified with terms. In our recipe site example, it then becomes easy to create pages displaying 'Main courses', '30 minute recipes', or '30 minute main courses and appetizers' by using terms on their own or in combination with others. There are a significant number of contributed modules which you to alter and extend the behavior of the core module for both display and organization of terms.