Glossary
Natal chart
A natal chart (or birth chart) records where every planet stood, in which zodiac sign and house, at your moment of birth as seen from your birthplace. It's the fixed reference everything else is computed from: planetary lines, composites, synastry.
The condition of a planet in the natal chart — its dignity, the aspects supporting or straining it — changes how that planet's line reads on the map. This is why two people's Venus lines are not interchangeable.