The foreshore, also called intertidal zone, is the zone between low tide and high tide on the shore. The alternation of the tides that reveals the substrate for more or less time depending on the phases of the Moon determines the humidity, salinity and temperature of the foreshore.
These variations lead to vertical ecological structuring of the foreshore into zones called the high intertidal zone, the mid intertidal zone and the low intertidal zone. The flora and fauna populations of these zones are distinct, depending on the organisms' needs for water, salinity and temperature.
The foreshore is divided into several zones corresponding to different ecological conditions. These shoreline zones are defined by the length of time they are exposed and therefore by the various tidal levels (high tide and low tide, spring tides and neap tides). © epimetheus, Flickr CC by 3.0