From http://www.w3schools.com (Copyright Refsnes Data)

HTML <hr> tag

Example

A horizontal line is marked up as follows:

This is some text <hr /> This is some text

The <hr> tag creates a horizontal line in an HTML page.

The <hr> tag is supported in all major browsers.

In HTML the <hr> tag has no end tag.

In XHTML the <hr> tag must be properly closed, like this: <hr />.

All "presentation attributes" of the hr element were deprecated in HTML 4.01, and are not supported in XHTML 1.0 Strict DTD.

Note: The hr element renders differently in different browsers.

DTD indicates in which DTD the attribute is allowed. S=Strict, T=Transitional, and F=Frameset.

Attribute	Value	Description	DTD
align	center left right	Deprecated. Use styles instead. Specifies the alignment of the horizontal rule.	TF
noshade	noshade	Deprecated. Use styles instead. When set to true the rule should render in a solid color, when set to false the rule should render in a two-color "groove".	TF
size	pixels	Deprecated. Use styles instead. Specifies the thickness (height) of the horizontal rule.	TF
width	pixels %	Deprecated. Use styles instead. Specifies the width of the horizontal rule.	TF

id, class, title, style, dir, lang, xml:lang

For a full description, go to Standard Attributes.

onclick, ondblclick, onmousedown, onmouseup, onmouseover, onmousemove, onmouseout, onkeypress, onkeydown, onkeyup

For a full description, go to Event Attributes.