Just like you can use <br /> to insert vertical space
into content,
you can use an inline spacer to insert and control
horizontal space.
The inline spacer is a marker element
that emphasizes the space in between content.
You use it when you do not want to
mark up content, but you still want to control the amount of space
in between content.
For example, if your page design requires extra space before sentences, it is not a good idea to mark up sentences, because that would prevent you from cutting across sentence boundaries with additional markup. Marking up the first word of a sentence would not be semantically accurate because the extra space separates sentences not words. The inline spacer solves this problem because it does not interfere with other markup. It is also semantically correct because its purpose is to mark up and emphasize space.