The ten Day Masters
One character out of eight carries the reading. It is the upper character of the day pillar, and everything else in the chart describes the conditions it stands in.
What a Day Master is
A chart is eight characters: four pairs, one pair for the year, the month, the day and the hour. Of the eight, one is the subject and the other seven are the conditions. That one is the upper character of the day pillar — ten possibilities, five phases in a yang and a yin form each — and the tradition calls it the 日主, the Day Master.
The ten are not ten personality types. Each is an image, and the image carries what the phase in that polarity is for, what it needs supplied, and what it will not tolerate. 甲 is timber and 乙 is the climbing plant; both are wood, and almost nothing said about one transfers to the other. The pages below give each image as the classical texts state it, with the Chinese and a plain rendering next to it.
A Day Master on its own settles less than most sites imply. What decides whether it is supported is the month it was born into, which is why every stem below also links to the twelve months of its own phase.
Cast the chart this page describes
The four pillars, the Day Master, the five-phase count, the day’s almanac read against the chart and the true solar time working — about 2,700 words — are free and need no account. The chart is computed in the browser; nothing about the birth is sent anywhere.