Hypertext Reference (HREF) is an HTML attribute that you use to specify a link destination or Uniform Resource Locator (URL). Most commonly you will see the HREF attribute paired with an anchor tag `<a>`.
The exact behavior of the HREF attribute depends on the element that is using it. For instance, when used with the `<a>` tag, it is referencing the location of an object expressed as a URL. When using the HREF attribute with the `<image>` tag, the HREF attribute is referencing the URL location of an image to render.
Additionally, an HREF may also reference a file on a server or a local directory. A directory can be considered a folder on a computer. For instance, you might wish to create a hyperlink that points to the main page of a website. Typically the main page of a website has the file name `index.html`, so instead of a full URL, you may simply type `index.html`. Please note that if the file is not in the same directory it may require you to add a `/` or a `../` to move into or out of the current directory.