Wordpress provides two useful ways of allowing you make content easy for your visitors to find. These are Categories and Tags. Using both can help make your site easier to navigate. But before we go any further you must remember: Never use a category or a tag only once! Why? Well, when you use either a category or tag just once, Wordpress will display that one post that has been tagged twice. Duplicate content is a definiate no no and can harm your sites Search engine placement.