Italicize (in handwriting, underscore) words under discussion.

Black  is an adjective, modifying cat.

Using Italics and Underlining (Darling et al) 
Brief Overview of Italics (Purdue OWL)

Italicize (in handwriting, underscore) letters of the alphabet spoken of as letters.

There is only one t  in commit.

Using Italics and Underlining (Darling et al) 
Brief Overview of Italics (Purdue OWL)

Italicize (in handwriting, underscore) foreign words or phrases.

He has savoir faire.

Using Italics and Underlining (Darling et al) 
Brief Overview of Italics (Purdue OWL)

Italicize (in handwriting, underscore) names of newspapers, magazines, literary compositions, musical compositions, pictures, movies, plays, and ships. 

Put quotation marks around the title of a short story or poem. 

Shakespeare wrote A Midsummer Night’s Dream.

Keats wrote "Ode to a Grecian Urn".

Using Italics and Underlining (Darling et al)
Brief Overview of Italics (Purdue OWL)