expressions - forget or forget about?

Apart from the difference between forget it and forget about it, what do you forget and what do you forget about?

Do you forget a face, someone's birthday or your date who is waiting for you?

Do you forget about your keys or the money you borrowed your friend? What are the criteria for which is/are acceptable?

In the M-W Learner's Dictionary is found the following, by Peter Sokolowski:

[W]hat's the difference between forget and forget about?

Forget about is used with a couple specific senses of forget. In the following senses, the use of about is optional.

1. When forget is used to mean "to stop thinking or caring about
   (someone)":

   
   
   
   
   
   • He was once a famous actor, but now most people have forgotten (about) him.
   
   
   
   • You shouldn't forget (about) your old friends.
   
   



2. When forget is used to mean "to stop thinking or caring about (something) on
   purpose":

   
   
   
   
   
   • We need to forget (about) our differences and learn to get along.
   
   
   • “I'm sorry I'm late.” “That's OK. Forget (about) it.” [=don't worry about it]
   
   
   • Forget about finding a way to escape—there's no way out of here.
   
   
   • I had almost forgotten about my car accident last year.
   
   
   

About can add some emphasis when something specific is forgotten, but sometimes the structure of the sentence changes:

• I forgot to pay the bill. = I forgot about paying the bill.

But can anyone add other details to the different usages?

Answer

You can forget about a lot of things, but you can forget less things.

Forget is a general word, forget about is more specific.

Generally speaking, both expressions are equivalent. The differences pop up in context. Forget about is used for properties of an item mostly, or an action with an item. Forget is to completely remove the item from "context".

For example,

• "I forgot my keys.": Person forgot their keys, as in it was left somewhere, and the person doesn't have it.


• "I forgot about my keys.": Person might have the keys, but forgot to Use it at the appropriate moment.


• "I want to forget about my keys.": Person would like to "un"know about its keys, or wants to bury the memories of it.


• "Forget about the keys!": Intent is to indicate that whoever it was addressed to won't get what the person asked for - right now, the keys.


• "Forget about it!": Not going to happen.

Take your forget a face example:

• "I forgot that face.": Person doesn't remember how someone's face looked like, like "I forgot how my Mom's face looks like.", when that person's mother might be dead, or unseen for a long time.


• "I forgot about that face.": Again, the didn't bring/didn't know/didn't use pattern. Or a more kind, non-direct way of saying one doesn't remember all the facial features - but not the entire face.

There can be different interpretations, but these are the general cases, i believe.