<br/> This is a tag for line breaks (for breaking). The tag does not have this, start or end tag etc. Using it inside the HTML element, you can break the line in any place and move it to the bottom line. Usually it is used inside <p> </ p> while writing address etc. There are also more on the application.

<p>123 text world<br/>world wide<br/>world</p>

<hr /> tag
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The hr tag is used to make long lines long. Such as

<p>World wide web</p>
<hr/>
<h2>This is a heading</h2>
<hr/>