Italics and underlines can be used interchangeably, but not at the same time. When typing, we use italics and underlines to identify titles of larger works, magazines, books, poems, newspapers, journals, etc. Italics are used when typing, while underlines are used when writing.
Now talking italics and underlines and this is a pretty simple concept but nonetheless I get a lot of errors with this and I have a lot of questions about it. So let's talk about it and the one main thing that you need to know is that, they are used interchangeably, not at the same time. So italics and underlines mean the same thing. My general rule of thumb is when you're typing, put it in italics, when you're handwriting since you obviously can't italicize your own handwriting unless you're very talented, go ahead and just underline it, alright. What we do is we just use them for titles of large work, things like books, magazines, movies and plays. So my general trick for remembering what I need to italicize or underline is that if the work contains smaller parts like articles or chapters or acts, then I know it's a large work that I need to make sure that I either underline or italicize. So let's take a look at some of these sentences. I've got "One of my favorite books is Jazz by Toni Morrison". So I know I've got a book here, obviously this book is pretty large. It's got chapters in it, so I want to make sure I underline it alright. "I can't wait to get home and catch up on my episodes of Damages" and that sentence already tells you that this show 'Damages' contains smaller items which are episodes so I know I need to underline "Damages". And then finally, "according to Popular Science iPhones keep track of where their owners go." We've got the name of a magazine that we're quoting here, so we want to make sure we indicate that it's the title of a large work by underlining it. So it's pretty simple here. The biggest thing I can remind you of is please don't use italics and underlining at the same time. They mean the same thing.