If a pin is in high impedance state, it can be pulled to high or low by an external device without much current flow. This means that the gpio pin can effectively assume three values: Without outside interference the voltage level will be determined.
High impedance pins on an ic may be a varied range of voltage anywhere between the negative and positive supply rails.
This is achieved by deactivating the input and output buffers, usually via the enable line. The pin is just flopping in the breeze. The pins are floating at. That means the pin is left open.
When it's an input, it's tristated, allowing the external chip to control its. Its state is indeterminate unless it is driven high or low externally. It’s nothing but keeping your pin floating by not connecting to high voltage state or the ground as shown in figure1.
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