The HTML tags neglected

<optgroup>

This tag is used to group related options in a drop-down list.

<select>
    <optgroup label="Outdoor Games">
        <option value="cricket">Cricket</option>
        <option value="football">Football</option>
    </optgroup>
    <optgroup label="Indoor Games">
        <option value="chess">Chess</option>
        <option value="ludo">Ludo</option>
    </optgroup>
</select>

<abbr>

This tag is used to define an abbreviation or an acronym.

<abbr title="Hypertext Markup Language">HTML</abbr>

<address>

This tag is used to define the contact information.

<address>
    Deshbandhu Para<br>
    Siliguri<br>
    West Bengal<br>
    India
</address>

<datalist>

This tag specifies a list of pre-defined options for an <input> element.

<input list='browsers' name='browsers'>
<datalist id='browsers'>
    <option value="Chrome">
    <option value="Firefox">
    <option value="Safari">
</datalist>
<input type="submit">

<wbr>

The tag specifies where in a text it would be ok to add a line-break when resized.

<p>ThisIsALong<wbr>WordThatWillBreak<wbr>WhenTheWindowIsResized</p>

All the above designs are displayed without the help of CSS.

Hope you enjoyed the post and learned a few things.