The coast is one of the most dynamic environments on the planet. It is where wave and tidal energy are expended to carry out erosion and transport; it is the meeting place of the hydrosphere, the lithosphere, and the atmosphere. The coastal zone is subject to constant change: minute by minute as waves break and currents move alongshore; daily with high and low tides; monthly with tidal cycles; yearly with seasonal changes in wave approach and storm energy; and over the longer term with changes of climate and sea level. This constant change can cause major problems for coastal communities and management of geologic resources.

There is much informal or inconsistent terminology used to define or describe the coast. According to Oertel (2005), coast and coastline should be used when referring to the boundary between land and water at a regional scale; shore and shoreline are terms reserved for the same boundary but at a local scale. The area commonly referred to as the coastal zone is not strictly defined, but rather includes all land and water areas affected by marine processes. This may include areas many miles inland where even the weakest of tidal forces can be felt. In common usage, one tends to think of the beach as the primary or maybe only coastal environment. And the beach may be the most prominent, or most well known, of the coastal environments. The beach can be defined as an accumulation of sediment, moved by waves and currents.