What a house is
Twelve slices of your day, not of the sky.
Signs divide the sky and are the same for everyone. Houses come from YOUR birthplace and time. Because the Earth turns once a day, the houses slide across the signs through the day.
What that means in practice
In practice: two people born the same day share a Sun sign, but if one was born in the morning and the other in the evening, that Sun lands in different houses. Career for one, inner world for the other.
Without a birth time, houses cannot be calculated. That is half the chart — worth tracking the time down.
What are houses calculated from?
They shift all day long, which is why the time is required.