Most websites are made of pages and posts. Posts are categorized eg overall heading with sub headings eg Footwear as the heading and Shoes/Boots as the sub heading. If posts are uncategorized, they could end up anywhere on the site. Pages do not necessarily need to be categorized. If they are, they become Parent and Child eg Shoes as the Parent, Heels/Sandal/Boots would be the Child Pages. There are also grandchild pages which are sub areas of the child pages eg Heels as the child page and Stilettos/Wedges as grandchild pages.