Ephemeris
A table, or an engine, giving the exact position of the Sun, Moon and planets for any date and time you ask for.
An ephemeris is simply a record of where things were, or will be: the Sun, Moon and every planet's position along the ecliptic, listed for a given date and time, or worked out on demand for any date and time at all. Printed ones used to fill whole books, one row per day; this site computes the same numbers directly from the underlying orbital mechanics, for the exact instant asked for rather than the nearest tabulated day. Every fact on every page here — a house cusp, an exact aspect, a moon phase — traces back to an ephemeris calculation first. The chart, the daily reading and the almanac are all just different ways of presenting the same underlying positions.