1. A navigation bar is an area on a web page that holds links to other pages and subpages on a website. They are typically found at either the top or sides of a web page, below the banner for horizontal bars or aligned left or right for vertical bars.
2. A navigation bar on a web page is typically created using a combination of <div>, <ul> and <li> elements. The <div> is used to contain the entire navigation area, the <ul> (Unordered List) is used to hold the links, and each <li> (List Item) contains one link to another page.
3. No, you don't need to have all your subpages created before creating a navigation bar. You can use placeholders for the links that you will update later once the subpages are created.
4. The "#" symbol can be used as a placeholder for a missing page in an anchor element. This ensures the link appears like a normal hyperlink, but clicking on it does not take you anywhere until the actual page link is added.