# Pole

The pole of coordinates is the origin in polar coordinates.

A pole is the centre of an inversion.

The pole of the straight line $p$ with respect to a conic is the point $P$ such that the line $p$ is the polar of the point $P$ with respect to the conic.

For poles of (analytic) functions see Pole (of a function). Sometimes the word "pole" is used for the point $(0,0,1)$ (North pole) or $(0,0,-1)$ (South pole) of the unit sphere in $\mathbf R^3$, with centre at the origin.