I2C is a simple communication standard intended to move small amounts of data a few inches between chips. See wikipedia.
On the Neo1973, we currently use the following addresses on the I2C bus:
Note that I2C addresses are 7 bit. The last bit, which is not part of the address, indicates whether this is a read or write operation. So "0001 000x" is 0x8, not 0x10.