Definition:
A birth chart is a map of where all the planets were in the sky at the exact moment and location of your birth.

What You Need:
• Birth date.
• Birth time (exact time is crucial)
• Birth location (city/town)

What It Contains:
• Sun sign (your core identity)
• Moon sign (your emotions)
• Rising sign/Ascendant (how you appear to others)
• Positions of all planets in signs.
• Positions of all planets in houses.
• Aspects (angles between planets)

Why Birth Time Matters:
• Changes your Rising sign (shifts every 2 hours)
• Determines your houses.
• Affects planet placements.
• Makes chart accurate vs. generic.

How to Read:
• Start with Sun, Moon, Rising (the "big three")
• Look at planetary placements.
• Examine house positions.
• Study aspects between planets.
• Synthesize all information.

Source:
Astrological practice, readings by Karyna at The Syncretist Realm, TheSyncretistRealm.com.