There are three main types of parallax:

1. Geocentric parallax (or diurnal or orbital parallax): angular difference between center of the Earth and the observation site on the surface.
2. If the object lies in the site’s horizon, the parallax value reaches its maximum. It is called horizontal parallax.
3. Heliocentric parallax (or annual parallax): angular difference between observations taken from centers of the Sun and the Earth.