Day Master is the core concept in BaZi (Eight Characters) fortune-telling, referring to the Heavenly Stem of the birth date, representing the native themselves. BaZi analysis centers on the Day Master; by assessing its strength or weakness (vigor or frailty), one determines favorable and unfavorable elements (Xishen and Yishen), thereby predicting fortune and misfortune. A strong Day Master can bear Wealth and Officer stars; a weak Day Master requires support from Seal or Friend elements.
The Day Master is simply the Heavenly Stem of the birth date, directly read from the Heavenly Stem of the Day Pillar in the BaZi chart. For example, a person born on Jia Zi day has Jia Wood as the Day Master; one born on Bing Yin day has Bing Fire as the Day Master.
A person born on Jia Zi day has Jia Wood as the Day Master. If born in Yin month, the Day Master is in seasonal command and vigorous; if born in You month, it is out of seasonal command and weak.