In reviewing Matt Cutts Qualities of a good site video, one of the questions that came up was the use of <b> v.s. <strong> and <i> v.s. <em> tags.

Accoring to W3.org 's html4 difinition for Issues Surrounding the Structuring of Text, <strong> tags belongs to Phrase elements, which also includes EM, DFN, CODE, SAMP, KBD, VAR, CITE, ABBR, and ACRONYM. EM and STRONG are used to indicate emphasis. The other phrase elements have particular significance in technical documents. These examples illustrate some of the phrase elements.

As HTML fontstyle elements, <b> tags and <i> tags are discouraged to use in favor of style sheets.

For those SEOers, the technical definition of these tags can be translated as follows:

* <b> tag present the encapsulated text in bold font, but is not meant to change the semantic meaning of such text. For example, if you read the sentence that contains text in side <b> tags you should read such encapsulated text with no special emphasis at all.

* <strong> tag presents the encapsulated text in bold font, and is also meant to change the semantic meaning of such text. For example, if you read the sentence that contains text in side <strong> tags you should read such encapsulated text louder.

* <i> tag presents the encapsulated text in italics, but is not meant to change the semantic meaning of such text. For example, if you read the sentence that contains text in side <i> tags you should read such encapsulated text with no special emphasis at all.

* <em> - Will present the encapsulated text in italics, and is also meant to change the semantic meaning of such text. For example, if you read the sentence that contains text in side <em> tags you should read such encapsulated text with additional emphasis.

for further discussion about BOLD tag vs STRONG tag and ITALIC tag vs EMPHASIS tags, please refer to this message board on webmasterworld.com.