The text-decoration property is used to add decoration to text in form of lines: above the text, below the text, or over the text, or to remove any existing decorations.

In CSS3, the text-decoration property is a shorthand for setting text-decoration-line, text-decoration-color, and text-decoration-style in one declaration. The absence of any of these values in the shorthand will set that value to its initial value (check the entries for each of these properties for details).

The text-decoration property can be declared without specifying values for the text-decoration-color and text-decoration-style properties. Those values will be set to their default values and are thus optional and not required, which means that the text-decoration property is fully backwards-compatible with CSS Levels 2 and 1, so even if a browser does not support the CSS3 text-decoration shorthand, it will still recognize and apply the style as part of the older CSS levels.

Before text-decoration became a shorthand in CSS3 it accepted 5 values: none, underline, overline, line-through, blink. The last value, blink, makes the text blink, but is deprecated and the specification allows browser to ignore this value, so you’re better off not using it, especially that the W3C Accessibility Guidelines recommend not using blinking text for better accessibility.

The text-decoration property accepts one or more whitespace-separated values.

Trivia & Notes

The line-through value is usually used to “strike out” lines of text that have been deleted or changed. Authors are encouraged in this case to use HTML elements such as <del> and <s> to preserve the semantics of such text, so that the meaning (Deletion) is still preserved even when styles are disabled on the page.

Anchor links have a default underline applied to them, which is good for accessibility, as some people depend on the presence of underlines to detect links on a page. So, even though removing the underlines is possible using text-decoration-line: none, it is highly recommended, for accessibility reasons, to keep the underlines or style them differently to match the overall style of the page, instead of completely removing them, unless another visual indication exists that indicates that a piece of text is in fact a link.