What is the origin of the idiom "break even" and when to use it?

The idiom "break even" may be related to the idea of a balance point, where all inputs and outputs are equal. The phrase has been in use in English since at least the mid-20th century, and it is often applied to situations where a business or project is just able to cover its costs, but not generate any additional income or profit. In general, the phrase is used to describe a situation where the outcome is neither positive nor negative, but rather neutral or balanced.