used to link alternatives.
a cup of tea or coffee
introducing a synonym or explanation of a preceding word or phrase.
the espionage novel, or, as it is known in the trade, the thriller
otherwise (used to introduce the consequences of something not being done or not being the case).
hurry up, or you'll miss it all
introducing an afterthought, usually in the form of a question.
John's indifference—or was it?—left her unsettled
to love is the one way to know or God or man