Definition:Subtraction

Also known as
The value $a - b$ (for any of the above definitions) is often called the difference between $a$ and $b$.

In this context, whether $a - b$ or $b - a$ is being referred to is often irrelevant, but it pays to be careful.

Historical Note
The symbol $-$ originated in commerce, along with the symbol $+$, where they were used by German merchants to distinguish underweight and overweight items.

They first appeared in print in $1481$.