- Adding a Paragraph
- Specifying Fine Print
- Marking Important and Emphasized Text
- Creating a Figure
- Indicating a Citation or Reference
- Quoting Text
- Specifying Time
- Explaining Abbreviations
- Defining a Term
- Creating Superscripts and Subscripts
- Adding Author Contact Information
- Noting Edits and Inaccurate Text
- Marking Up Code
- Using Preformatted Text
- Highlighting Text
- Creating a Line Break
- Creating Spans
- Other Elements
This chapter is from the book
This chapter is from the book
This chapter is from the book
Defining a Term
In the print world, it’s customary to differentiate a term visually when you define it. Typically, this is done with italics; subsequent uses of the term are not italicized.
In HTML, when you define a term, you differentiate it semantically with the dfn element. You wrap its tags only around the term you’re defining, not around the definition 
. And just as in print convention, subsequent uses of the term are not marked with dfn, because you aren’t defining them again. (HTML refers to the point where you define a term as the “defining instance of a term.”)
Note that although pleonasm appears twice in the example, dfn marks only the second one, because that’s when I defined the term. Similarly, if I were to use pleonasm subsequently in the document, I wouldn’t use dfn. Although browsers style dfn text differently than normal text 
, what’s important is that the term is marked up differently. Also, you don’t have to use the cite element each time you use dfn, just when you reference a source.
)
To mark the defining instance of a term
- Type <dfn>.
- Type the term you wish to define.
- Type </dfn>.