A pseduo class provides a means of defining properties for elements that are not available through HTML tags. For example, should you want to change the colour of a link when the mouse is moved over it, there is a hover pseudo class that may be associated with the anchor tag. The following example would set the link colour to teal if the mouse is moved over the link.

a:hover
{
    color: #008080;
}

Priority of Pseudo Classes with the Anchor Tag

When specifying styles for the anchor element's psuedo classes, the order is important. When you define styles for the same elements, the styles for that element are combined. When there are conflicting styles, the latest one overrides previous definitions of the style (which is inkeeping with the cascading concept, and true for all elements). The least significant style should be written first, and the most significant style written last. With the anchor element, this would be link, visited, hover, then active. If you define a basic style for the anchor element, it should be positioned before the pseudo classes.

Correctly Ordered Pseudo Classes

a:link
{
    text-decoration: none;
    color: #fc0;
    background: transparent;
}
a:visited
{
    text-decoration: none;
    color: #999;
    background: transparent;
}
a:hover
{
    text-decoration: underline;
    color: #fc0;
    background: transparent;
}
a:active
{
    text-decoration: underline;
    color: #603;
    background: transparent;
}

The following table shows the basic CSS Pseudo classes you may use.

The following example uses the first-leter and first-line pseudo classes to define a font size to start a new paragraph.

p.waffle:first-letter
{
    font-size:xx-large;
}
p.waffle:first-line
{
    font-size:large;
}

As an example, this paragraph has been formatted using the style outlined above. The style may either be isolated to a specific region within your HTML document, like this one, or applied to all documents. Applying the style to all of your documents ensures you have a consistent style. At a later date, should you decide to change the formatting, it's simply a case of changing one style sheet rather than editing all HTML documents containing that style. Yes I am rambling on a bit, but I wanted to make this a decent size paragraph.