Sometimes it's not what you write but how you write it. Quite literally. Case in point - a study that tested participants capability of distinguishing between medications with similar sounding names. The finding? Highlighted text is more noticeable than bolding, italicizing or even capitalizing. As you recall, even the font matters. And speaking of fonts - did you know that there are only two categories? Yep, serifs and sans-serifs. Times New Roman is an example of a serif. In fact, the serif font actually originated with the Romans. Sans-serifs are more blunt in appearance. Calibri is an example of a sans-serif.
In general, serifs are considered more readable than sans-serifs and therefore are used more for text.