The APA manual requires all references to book titles to appear in italics. Therefore, when preparing the bibliography of a paper that uses APA style, you must italicize all book titles. This requirement also applies to book titles mentioned in the text of the paper.
Scientific papers and legal scholarship frequently employ foreign words and jargon. The APA style manual specifies that words borrowed from other languages also must be italicized. Therefore, the APA style requires italics type face for abbreviated terms borrowed from Latin, including "i.e." and "e.g."
APA style rules require the use of italics to alert the reader that a term has a special meaning. Therefore, if you are using a term of art or a word that is meant to be cast ironically or as slang, italicize the word. APA style requires the use of italics only in the first instance that the word or terminology appears in the paper. All subsequent use of the term can be in the regular type face (font).
Italics type face adds emphasis to a word or a phrase. In such a case, the choice to use italics belongs to the author. The APA style manual recognizes that the use of italics in such a case is to draw the reader's attention to a particular point that is being made by the author.