Coast - Zone where land meets sea
Coastline - Edge of a coast
Shore - Area between high tide and low tide
Waves - Moving swells on the surface of the water caused by friction of the wind [Wind pushes waves]
Tides - rise and fall of the ocean’s waters caused by gravitational pull of the moon and sun. Tidal ranges vary between coasts – The sea rises to high tide (high water mark) and falls to low tide (low water mark) normally twice a day.
Currents - steady, predictable flow of fluid within a larger body of that fluid

HOW DO THEY WORK -
Strong swash - Pushes pebbles upwards - weak backwash - leaves the pebbles up