Here's why:
* Italics are the standard way to indicate titles of longer works, such as books, magazines, newspapers, and journals.
* Underlining was a common way to indicate italics before computers became widespread, but it's no longer considered standard practice.
* Quotation marks are used for titles of shorter works, such as songs, poems, articles, and short stories.
Example:
Instead of "Time Magazine" or "Time Magazine", it should be *Time*.