The most primary and obvious division is based on the two fold division of the day into two halves – the day and night. In the sky, the Sun dominates the day and the Moon dominates the night. These luminaries are, therefore referred to as the Lords of the day and night respectively. Yet when we compare the waking hours of man, the tendency is to stay awake for most of the daytime while man is awake for only the initial part of the night. Comparatively, the Sun is a greater lord than the Moon and because of this, the Sun is also regarded as the lord of the fill 24 hour day.
There are various types of horā charts and the manner in which they are drawn i.e. the principle used indicates the application of the horā chart. We have the most basic Parāśara Horā (D2 Chart) and in addition, we also have Gola Horā (D2-G) and the Kasinath Horā (D2-K).
There are umpteen horā charts out there and each one of them has some use. Do not use a chart unless you fully understand the principle in which it is drawn. It is these underlying principles that inform about its use and application. Starting with the etymology, we have a few lessons on Horā. Of particular importance is the Parāśara Horā (D2 Chart) which shows the light in the planets and which can indicate the extent of the light of life in the being. The periods of such planets which are without much light are definitely a souce of suffering and sorrow, and even death.