The state of the electron in space is represented by $\psi (x,y,z)$. The probability of finding an electron at a point in space is given by

Orbital wave function ψ is a mathematical function for an atomic orbital. The square of the wave function, ψ²$\left(x,y,z\right)$ is called probability density and is always positive. Its value defines the probability of finding the electron around nucleus.