Lists
HTML provides several ways to display lists of information:
-
unordered lists: bulleted lists (like this one)
-
ordered lists: numbered lists, procedures, formal outlines
-
definition lists: lists of terms and definitions
Lists are different from anything we’ve covered so far, because generating a list requires at least two elements working together.
Ordered Lists
Ordered lists are contained by an ol
element. Within the <ol>
and </ol> tags, each
list item is defined by an li element:
Example 2.17. Ordered Lists
<h3>My Dot-com Business Plan</h3>
<ol>
<li>Buy domain name</li>
<li>Put up website</li>
<li>???</li>
<li>Profit!</li>
</ol>
The default ordered list uses arabic numerals (1, 2, 3, …), but you can easily alter this behavior.
Directly within the ol element, you can only
include li elements. However, within the
li elements you may place nearly any HTML content
that you want: text, paragraphs, images, even another list.
Example 2.18. Nested Ordered List
<h3>Schedule for Monday</h3>
<ol style="list-style-type: upper-roman">
<li>Suppress Gaul
<ol style="list-style-type: upper-alpha">
<li>Two more legions or three?</li>
<li>Where to put victory arch? Forum's looking
crowded...</li>
</ol>
</li>
<li>Have Cicero killed</li>
<li>Lunch</li>
<li>Head-and-hands-on-pike viewing at the Forum (casual
dress ok?)</li>
</ol>
Placing one list within another is a nested list. The
outer list will use upper-case Roman numerals, and the inner
list will start counting independently, using upper-case
letters. There are a large number of available
list-style-types for ordered lists. The most common and
well-supported values are upper-roman,
lower-roman, upper-alpha,
lower-alpha, and the default, decimal.
If for some reason the browser doesn’t understand the value
you specify, it just falls back to the default (decimal
numbers).
You can use ol for any list of items where
the order is important. This includes outlines, procedures,
TODO lists, lists of ranked items.
Unordered List
Unordered lists are similar to ordered lists, except that
they do not have a particular order. Unordered lists even
recycle the li element, which makes it easy to
turn an ordered list into an unordered list and vice-versa.
All you need do is turn your ols into uls:
Example 2.19. Unordered List
<h3>My Dot-com Business Plan</h3>
<ul style="list-style-type: square; color: #009900">
<li>Buy domain name</li>
<li>Put up website</li>
<li style="list-style-type: disc; color: #ff0000">???</li>
<li>Profit!</li>
</ul>
In the parent element ul, we’ve specified
that the list should be green and that the bullets should be
squares. We overrode this behavior in the third bullet
point, specifying a red, circular bullet. Notice how the
style cascades from the parent element to the child elements
― each bullet takes on the characteristics of its parent,
unless we specify otherwise.
Ordered and unordered lists indent everything enclosed by
the ul or ol block. You might be
tempted to use ul to indent any old HTML:
<ul> <p>This is an indented paragraph.</p> </ul>
Don’t do this. This is incorrect HTML, and there are
better ways to achieve the same effect, as we’ll see in
“Align and Indent”. While we’re on the subject, li
elements must always be enclosed by a ul or
ol element. Don’t put li elements
directly in the body of the document; this is
also bad practice.
Definition Lists
A definition list provides a list of terms and definitions. Definition lists require three elements to construct:
-
dl: Denotes the definition list itself. Within thedlyou may only includedtandddelements. -
dt: Denotes a term within the definition list. Within thedtyou may only include inline content, such as plain text and inline style elements. -
dd: Denotes a definition for a term. Within theddyou may include any block or inline content: paragraphs, other lists, whatever you like.
A definition list consists of terms (dt)
immediately followed by definitions (dd).
Example 2.20. Definition List
<h1>The Devil's Dictionary</h2>
<dl>
<dt>ABSURDITY, n.</dt>
<dd>A statement or belief manifestly inconsistent with
one's own opinion.</dd>
<dt>ACADEME, n.</dt>
<dd>An ancient school where morality and philosophy were
taught.</dd>
<dt>ACADEMY, n.</dt>
<dd>[from ACADEME] A modern school where football is
taught.</dd>
<dt>ACCIDENT, n.</dt>
<dd>An inevitable occurrence due to the action of
immutable
natural laws.</dd>
</dl>
You may provide multiple definitions for a term, or even
multiple definitions and multiple terms, although
this is less common. Some people also use definition lists
to mark up screenplays and other exchanges of dialogue: the
speaker is a dt and their dialogue is a
dd. If you’re writing technical manuals (perish the
thought!), you can use definition lists to document
variables, interface components, and more. Definition lists
are good for any “listed information that comes in pairs.”
Congratulations, you’ve finished the basic section! In the next section we learn about advanced font styling, alignment, margins, and borders. Read on for more…
See Also
- Next Page: Styling Basics
- Previous Page: Images



