My understanding of the semantics of <strong> and <em> vs. <b> and <i> is that the former indicate a stress, emphasis, offset or importance that would be expressed verbally, if reading aloud.
On the other hand, the <b> and <i> tags indicate stress, emphasis, offset or importance that is visual or typographic. I frequently see people arguing that <strong> is the most semantic element to use for a term or keyword because it is the most "important," but in a situation where you would never change the way you read the sentence verbally, but rather, just want the typographic indication that it's a term. To me, I think this is coming from some ambiguity in the word "important" that causes people to fundamentally misunderstand when to use <strong> vs <b>. Is my understanding (i.e., thinking in terms of visual vs. verbal offset as a way of clarifying the meaning of the definitions) right here, and if so, is there some sort of less ambiguous, authoritative document that I can point people to when these discussions come up? Semantics conversations always seem to come back to a fundamental disagreement about the meaning of the words used in the W3C specification.