They are questions that can be used to ask for an explanation about something.

HOW COME? Used to ask Why something has happened or the reason for something.

“How come” is the abbreviated version of “How come it came to be that way?”

Why’ is mainly to know the reason, cause, or purpose for something. It is more of an authoritative question. It demands an answer.


Why is she here? (I want to know the reason)

How come she's here? (I thought she wasn’t going to come.)

Other Examples:

Why was she late?
Why does she have to go?
Why did you go to Argentina?
Why did she clean your mess?
Why didn't you see the play with them?

How come she was late?
How come she has to go?
How come you went to Argentina?
How come she cleaned your mess?
How come you didn't see the play with them?