What is the origin of the idiom "sink or swim" and when to use it?

The origin of this idiom comes from swimming, where a person is either able to stay afloat and swim or will sink and drown. The idiom is used to describe a situation where someone is left with no choice but to succeed or fail on their own, without any help or support. The phrase suggests that the situation is challenging, and that the outcome is uncertain, but that the person must do their best to succeed.