Black Scholes $ ( \;)^+$ Notation Question Came across an exercise involving the Black Scholes formula which uses:

$E[(S_{T}-K)^{+}|F_{t}]$

What is the $\;(\;)^{+}\;$ in the expression? Is this some kind of operator?

Thanks.
The expression $(x)^+$ is defined as $(\bullet)^+ : x \mapsto \max(0,x)$ for $x\in\mathbb{R}$.
It simply tells you that you take the positive payoff, that is the difference between current price and the strike price, otherwise if you get a negative, the result is zero. When you are dealing options, it shows you that when $S_T&lt;K$, at time $T$ the option is worthless.