The <address> tag is used to write addresses on a document. It can be useful when you go back to your source code to figure out, a little like comment, what was that about but is shown in the browser. What I mean by that is that there is no need of using this and it even takes a few more typing to insert this but when you read back your code it is cleaner and clearer. You can also make it an habit of using it in footer of document to put your address, copyright, etc.