I²C Chip Select
The I²C bus selects a destination device by its address. In some cases, a device might have a fixed address, meaning only one device of that type can appear on the bus. However, in most cases, a device's address is determined by its hardware configuration. In the image above, a 24LC256 serial EEPROM is depicted showing its three-chip select pins which correspond to the three address bits in the I²C signal. The address the device will respond to depends on which pins are connected to the positive supply and which pins are connected to ground.