Human Design readers are trained to be able to tell you things about you by looking at your bodygraph chart.
Based on what is coloured in and which numbers are written, or which direction the arrows are pointed, a reader can decipher where you have more consistent energy output, where you receive energies from external sources and what your Type, Authority, Profile, Channels and Incarnation cross is.
Below you will see my chart from 3 different software programs but as you can see, it is the same chart.
How to read a Human Design Chart
Below is a blank one with no definition in it. It labels the 9 centres
ENERGY CENTRES
The "centres" in a Human Design bodygraph chart are the squares and triangle shapes. There is also one that is diamond shaped. The type of shape it is or the colour it is does not hold significance, however what a reader would look at is whether or not they are coloured in.
If a shape is coloured in, that means it is "defined". Defined means it is a consistent source of energy in one's body that they produce and emanate outwardly. Some people also use the word "activated" instead of "defined".
If a shape is white or not coloured in, it means it is “undefined". This means this centre's specific somatic energy is absorbed like a sponge, and does not emanate it's on energy, but amplifies and reflects the energy that it is receiving.
In one metaphor that might help you, an undefined centre is like a ceiling fan that circulates air, where define centre is like a heater that emanates hot air.
When a centre has no gates defined, meaning none of the little numbers inside of it are coloured in, then it is considered "open". It is a centre that is extremely susceptible to absorbing energies from others.
This is where a lot of conditioning can occur because of external influence. However, when someone can receive energy in these centres and not identify with them or can let it circulate back out instead of letting it sit there, they can learn a lot about life and gain immense wisdom about that energy centre's themes.
GATES
The small numbers you see written in each centre is called a "gate". There are 64 gates which come from the 64 i'Ching hexagrams. Each of them carry the same themes from the i'Ching but have been interpreted slightly differently in Human Design. A gate can either be defined or undefined. As you can see in the bodygraph image, there are lines that connect gates to each other. Those lines are called "channels".
Gates have a special relationship to the one that is on the other end of a channel. Energy wants to connect to other energy in our universe. So, when a gate is defined, but the other side is not, then that gate is called a "a hanging gate".
A hanging gate reaches out to the other side, just as the undefined gate wants to as well, they both want to connect to the other side's energy but in this dynamic, the undefined gate becomes more susceptible to conditioning.
CHANNELS
Whenever there is a centre that is coloured in or defined, it means there is a channel connecting it to another centre, where both centres on either end are defined. A channel is a combination of the energies of the two gates that it connects. A channel is a specific gift, talent or skill that you have access to consistently, although some work in pulses or cycles.
For example, if Gate 4 in the Ajna connects with Gate 63 in the Head, it would form the channel 63-4 The Channel of Logic. Gate 63 is the Gate of Doubt and Gate 4 is the Gate of Answers. So, there is doubting, skeptical energy that wants to verify ideas to see if they're true in Gate 63. And then Gate 4 tends to create logical answers to these doubts. So, the full channel tends to constantly doubt what it hears and comes up with logical answers. Whether these answers are verified or not is another thing. But using logic, this channel has the ability to hypothesize answers that seem or sound logical.
However, if someone only had Gate 63 defined and not Gate 4, then this person might experience the doubts and the internally sourced pressure to question things but they may have a hard time coming up with logical hypothetical answers compared to someone who does have Gate 4 defined.
If you'd like to learn how to derive the profile numbers of someone's bodygraph, you can read this.
If you'd like to learn how to understand the columns on either side of the chart, you can read this.