덜 일반적으로 사용되지만 Xhtml_HTML/Xhtml_Web 페이지 제작에서는 매우 유용한 태그입니다.

<code class="html"><span class="tag"><head</span><span class="tag">></span><!&mdash;写在head标签之间--<span class="tag">> <br><span class="tag"><base</span><span class="aname"> href</span>=<span class="avalue">"http://www.qq.com/"</span> <span class="tag">/></span> <!&mdash;将默认链接定义为http://www.qq.com/--<span class="tag">> <br><span class="tag"><base</span><span class="aname"> target</span>=<span class="avalue">"_blank"</span> <span class="tag">/></span> <!&mdash;将默认链接目标定义为新窗口中打开--<span class="tag">> <br><span class="tag"></head></span></code><p><br><font size="4"><strong><caption>标签</strong></font><br>    <strong>作用：</strong>caption标签用来定义表格的标题，给表格定义一个标题，来说明这个表格是干什么的，岂不是很有“语义”，caption应该写在table之后，默认的样式是居中显示在表格的顶部。你可以通过css来改变它的样式。<br>    <strong>用法：</strong><br></p>

<code class="html"><span class="tag"><table</span><span class="aname"> width</span>=<span class="avalue">"200"</span><span class="aname"> border</span>=<span class="avalue">"1"</span> <span class="tag">></span> <br><span class="tag"><caption</span><span class="tag">></span> <span class="mlcom"><!--caption应该写在table之后--></span> <br>其实我是caption <br><span class="tag"></caption></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><td</span><span class="tag">></span><span class="entity"> </span><span class="tag"></td></span> <br><span class="tag"><td</span><span class="tag">></span><span class="entity"> </span><span class="tag"></td></span> <br><span class="tag"></tr></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><td</span><span class="tag">></span><span class="entity"> </span><span class="tag"></td></span> <br><span class="tag"><td</span><span class="tag">></span><span class="entity"> </span><span class="tag"></td></span> <br><span class="tag"></tr></span> <br><span class="tag"></table></span></code><p><br><font size="4"><strong><thead>标签、<tbody>标签、<tfoot>标签</strong></font><br>    作用：thead、tfoot 
以及 
tbody标签跟他们的名字那样，分别是表格的头部（很多人只是用th）、主题、和底部，他们能让表格更加语义化的同时，也能让我们更加方便的控制表格的表现。国外还有人用很变态地方法用这三个表其做出标题能跟随表格，或者tbody固定高度，多出的行数出现滚动条。有兴趣的可以搜素下或者是这做一下。<br>注意：<font color="#ff0000">如果您使用 thead、tfoot 以及 tbody 
元素，您就必须使用全部的元素。它们的出现次序是：thead、tfoot、tbody，这样浏览器就可以在收到所有数据前呈现页脚了。</font><br>    <strong>用法：</strong><br></p>

<code class="html"><span class="tag"><table</span><span class="aname"> border</span>=<span class="avalue">"1"</span><span class="tag">></span> <br><span class="tag"><thead</span><span class="tag">></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><th</span><span class="tag">></span>科目<span class="tag"></th></span> <br><span class="tag"><th</span><span class="tag">></span>分数<span class="tag"></th></span> <br><span class="tag"></tr></span> <br><span class="tag"></thead></span> <br><span class="tag"><tfoot</span><span class="tag">></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><td</span><span class="tag">></span>总分<span class="tag"></td></span> <br><span class="tag"><td</span><span class="tag">></span>159<span class="tag"></td></span> <br><span class="tag"></tr></span> <br><span class="tag"></tfoot></span> <br> <br><span class="tag"><tbody</span><span class="tag">></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><td</span><span class="tag">></span>语文<span class="tag"></td></span> <br><span class="tag"><td</span><span class="tag">></span>99<span class="tag"></td></span> <br><span class="tag"></tr></span> <br><span class="tag"><tr</span><span class="tag">></span> <br><span class="tag"><td</span><span class="tag">></span>数学<span class="tag"></td></span> <br><span class="tag"><td</span><span class="tag">></span>60<span class="tag"></td></span> <br><span class="tag"></tr></span> <br><span class="tag"></tbody></span> <br><span class="tag"></table></span></code><p><br><font size="4"><strong><fieldset>标签和<legend>标签</strong></font><br>    <strong>作用：</strong><fieldset>元素用来分类表单中的元素，而<legend>则能给这个组定义一个标题。你一定见过类似下面domo的布局吧！他们也可以通过css定义样式。<br>    <strong>用法:</strong><br></p>

<code class="html"><span class="tag"><form</span><span class="tag">></span> <br><span class="tag"><fieldset</span><span class="tag">></span> <br><span class="tag"><legend</span><span class="tag">></span>基本信息<span class="tag"></legend></span> <br>姓名: <span class="tag"><input</span><span class="aname"> type</span>=<span class="avalue">"text"</span> <span class="tag">/></span> <br>性别: <span class="tag"><input</span><span class="aname"> type</span>=<span class="avalue">"text"</span> <span class="tag">/></span> <br><span class="tag"></fieldset></span> <br><span class="tag"></form></span></code><p><br><font size="4"><strong><sub> 标签和<sup> 标签</strong></font><br>    作用：<sub> 
标签和<sub> 
标签分别是上标和下标，虽然他们在各个浏览器的表现不一样，你<br>同样可以使用css定义他们的样式。<br>    <strong>用法：</strong><br></p>

<code class="html">2<span class="tag"><sup</span><span class="tag">></span>我是上标<span class="tag"></sup></span> <br>2<span class="tag"><sub</span><span class="tag">></span>我是下标<span class="tag"></sub></span></code><p><br><font size="4"><strong><label>标签</strong></font><br>    <strong>作用：</strong>label 
标签的使用可以扩大表单的点击区域来改进表单的易用性。看看下面的用法：点击文字的时候相当于点击了单选控件，这样用户体验是不是会更好一些？<br>    <strong>用法：</strong><br></p>

<code class="html"><span class="tag"><form</span><span class="tag">></span> <br><span class="tag"><label</span><span class="aname"> for</span>=<span class="avalue">"nan"</span><span class="tag">></span>先生<span class="tag"></label></span> <br><span class="tag"><input</span><span class="aname"> type</span>=<span class="avalue">"radio"</span><span class="aname"> name</span>=<span class="avalue">"sex"</span><span class="aname"> id</span>=<span class="avalue">"nan"</span> <span class="tag">/></span> <br><span class="tag"><br</span> <span class="tag">/></span> <br><span class="tag"><label</span><span class="aname"> for</span>=<span class="avalue">"nv"</span><span class="tag">></span>女士<span class="tag"></label></span> <br><span class="tag"><input</span><span class="aname"> type</span>=<span class="avalue">"radio"</span><span class="aname"> name</span>=<span class="avalue">"sex"</span><span class="aname"> id</span>=<span class="avalue">"nv"</span> <span class="tag">/></span> <br><span class="tag"></form></span></code><br><font size="4"><strong><optgroup> 标签</strong></font><br>    <strong>作用：</strong><option></option> 
标签可以给select中的option进行分组，这在下拉项目很多的时候很有用，配合label标签给每组命名。你也可以像淘宝那样给每组用css定义不同的颜色。<br>    <strong>用法：</strong><br>

<code class="html"><span class="tag"><select</span><span class="tag">></span> <br><span class="tag"><optgroup</span><span class="aname"> label</span>=<span class="avalue">"自驾游"</span><span class="tag">></span> <span class="mlcom"><!--配合label标签给每组命名--></span> <br><span class="tag"><option</span><span class="tag">></span>省内<span class="tag"></option></span> <br><span class="tag"><option</span><span class="tag">></span>省外<span class="tag"></option></span> <br><span class="tag"></optgroup></span> <br><span class="tag"><optgroup</span><span class="aname"> label</span>=<span class="avalue">"旅行社"</span><span class="tag">></span> <br><span class="tag"><option</span><span class="tag">></span>省内<span class="tag"></option></span> <br><span class="tag"><option</span><span class="tag">></span>省外<span class="tag"></option></span> <br><span class="tag"><option</span><span class="tag">></span>国外<span class="tag"></option></span> <br><span class="tag"></optgroup></span> <br><span class="tag"></select></span></code><br>    你如果对更多的xhtml标签感兴趣，可以考虑看一看《HTML和XHTML权威指南》这本书，你也能在网上找到电子版的。我看过英文影印版的，虽然是英文但也不是太难看懂。<br>    你要是知道其他很有用的标签告诉我们吧！