The chart has three building blocks:
Centers (the 9 shapes)
Each center is an energy hub associated with a specific function — thinking, feeling, intuition, willpower, identity, etc. When a center is colored in (defined), that energy is consistent and reliable in you. When it's white (undefined), you absorb and amplify that energy from the people around you.
Neither is better. Defined centers are your fixed broadcast. Undefined centers are where you go to school — where conditioning happens and where wisdom eventually develops.
Channels (the lines between centers)
A channel connects two centers and creates a fixed energy flow. You have a channel when both gates on either end are activated. Channels are what define your centers — no channels, no definition.
Gates (the numbered points)
Each of the 64 gates sits inside a center and carries a specific theme. Having a gate means you carry that theme as part of your design. A gate that's alone (without its partner on the other end of the channel) is called a hanging gate — it's looking for the other half, which it finds in other people's charts or through planetary transits.