A full URL (Uniform Resource Locator) is needed when a page links to another one that is on a different computer. Often pages link to others that are in the same directory. In that case, using just the file name of the linked-to page will work:
<a href="PageB.html">Words that the user sees</A>
A web browser shows the "Words that the user sees" underlined and in blue (depending on the preferences setting of the browser.) The user clicks on them to go to the linked-to page.
Hyperlinks go practically anywhere in your web page. The following shows a link that is part of a paragraph: