Appositives

 They are used in front of other words to identify or change your name. Its rename another noun right beside it. 

Commas are used when names are specific. 

Example: 

-Michelle Obama, president Obama wife.

Below in the following image we can see some other examples that further detail this explanation: 

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An example of this topic can be found in the 1991 interview with Alexander Theroux:

"The essence of loneliness is that one both remembers and hopes, albeit in vain, in the midst of one's dissolution. Nothing normal compared to is a consolation, a kind of hibernation, a tundra of arctic whiteness that denies feeling and wants."

(Taken from "An Interview with Alexander Theroux" published by the Contemporary Fiction Magazine of the year 1991)