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

HTML <colgroup> tag

Example

Two colgroup elements that specify different alignment and style for the three columns in the table (notice that the first colgroup element spans two columns):

<table width="100%" border="1">
<colgroup span="2" align="left"></colgroup>
<colgroup align="right" style="color:#0000FF;"></colgroup>
<tr>
    <th>ISBN</th>
    <th>Title</th>
    <th>Price</th>
</tr>
<tr>
    <td>3476896</td>
    <td>My first HTML</td>
    <td>$53</td>
</tr>
</table>

Try it yourself!

Definition and Usage

The <colgroup> tag is used to group columns in a table for formatting.

The <colgroup> tag is useful for applying styles to entire columns, instead of repeating the styles for each cell, for each row.

The <colgroup> tag can only be used inside a table element.

Browser Support

The <colgroup> tag is only supported by Internet Explorer and Opera.

Differences Between HTML and XHTML

NONE

Tips and Notes

Tips: Add the class attribute to the <colgroup> tag, and let CSS take care of alignment, widths, colors, etc.!

Also have a look at the <col> tag.

Optional Attributes

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

Attribute	Value	Description	DTD
align	right left center justify char	Defines the horizontal alignment of the contents in the column group	STF
char	character	Defines a character to use to align text on (use with align="char")	STF
charoff	character-offset	Defines an alignment offset to the first character to align on, as set with char	STF
span	number	Defines the number of columns the <colgroup> should span	STF
valign	top middle bottom baseline	Defines the vertical alignment of the contents in the column group	STF
width	% pixels relative_length	Defines the width of the column group. Note: The width attribute can be overridden by settings in <col>!	STF

Standard Attributes

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

For a full description, go to Standard Attributes.

Event Attributes

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

For a full description, go to Event Attributes.