Intertidal inhabitants are tiny compared to us humans. Standing above the tidepools in our rubber boots, we are giants. We can look at the intertidal community from above, the same way we look at our own terrestrial landscape through the window of an airplane.
The bottom of these rocks is always underwater, even during low tide. The top of the rocks is often exposed to air, and is only underwater when the tide is high. This creates a gradient in the physical conditions on the rocks: the bottom is wetter, and the top is drier. This gradient is the reason why there are different zones in the intertidal. Low-, mid-, and high-tide zones are home to different species, each adapted to living in that particular zone.