In the past, you didn't need to enclose your paragraphs
with the paragraph tags, but now it is advisable to do so.
Actually, HTML is forgiving enough that it wouldn't be
a problem if you didn't, but you can't count on that
in the future, when XML rules.

The line break tag gives you the ability
to tell HTML where to break your text
instead of letting the browser do it for you.

To make use of the horizontal rule, just place
it wherever you want the rule to be.

          This paragraph was indented
using the nonbreaking space entity

This paragraph was indented
using one blockquote elemement

This paragraph was indented
using two blockquote elements