MagisterCultuum
Great Sage
Originally the use of Italics represented a misunderstanding that led the Italians to think that Carolinian Minuscule was the proper ancient style of writing that Renaissance Italians wanted to recreate.
Italicized : Underlined :: Bold : ALL CAPS
All four methods can be used for emphasis. Bolding is equivalent to all caps and provides more emphasis than italics/underlining, enough to be considered overly forceful or rude. Italics and bolding are more formal and preferred in print. Underlining and all caps are easier to do by hand/discern in handwriting and are thus preferred in handwritten documents. Traditionally writers would give their publisher handwritten drafts in which underlining was used to indicate the portions that should be italicized once in print. I think all caps may also have been how they told their publishers to use a bold font, ut I'm less certain about that.
Italics may also be used to indicate the use of a foreign word, or in block quotes instead of quotation marks.
Italicized : Underlined :: Bold : ALL CAPS
All four methods can be used for emphasis. Bolding is equivalent to all caps and provides more emphasis than italics/underlining, enough to be considered overly forceful or rude. Italics and bolding are more formal and preferred in print. Underlining and all caps are easier to do by hand/discern in handwriting and are thus preferred in handwritten documents. Traditionally writers would give their publisher handwritten drafts in which underlining was used to indicate the portions that should be italicized once in print. I think all caps may also have been how they told their publishers to use a bold font, ut I'm less certain about that.
Italics may also be used to indicate the use of a foreign word, or in block quotes instead of quotation marks.