The cumulative Normal distribution function describes the probability of a Normal random variable falling in the interval \((-\infty, x]\).
It is defined as:
/[
F(x;\,\mu,\sigma^2)
= \Phi\left(\frac{x-\mu}{\sigma}\right)
= \frac12\left[\, 1 + \operatorname{erf}\left(\frac{x-\mu}{\sigma\sqrt{2}}\right)\,\right],\quad x\in\mathbb{R}
/]
The R equivalent function is
pnorm.