A beach is a strip of coastal land that borders a body of water, often with a sandy shore. This land is subject to constant erosion by waves and winds that carry sand and other loose materials from one place to another, changing the shape of beaches every day. Beaches also have a variety of marine organisms, from tiny single-celled algae to crabs and sea anemones.
The characteristics of a beach depend on the type and amount of sediment that is present, the speed of currents and wind, and the turbidity of the surrounding ocean waters. A beach may have a dunes or bluffs on its sides, and it can be covered with a thick layer of sand that is compacted by the weight of people and animals walking on it. Beaches that are dominated by plants with complex network root systems can be more resistant to erosion, as these plants slow the flow of water and wind around them.
Unlike most other terrestrial habitats, the sea is a very dynamic environment. Its constantly ebbing and flowing water, currents and sand transports, moves and deposits materials at an amazing rate, and creates many different types of beaches. The most common types of beaches are sand and shingle beaches. These are made of sand particles that have been eroded from rocks offshore and then washed up by waves. Other types of beaches are rocky coastlines that have been shaped by wave action into more natural forms, such as coves and cliffs.
A beach can be a popular recreational area, with the most famous being Atlantic and Pacific coasts of the United States. They have a variety of facilities for public use, including lifeguard stations, changing rooms, showers and shacks. Many beaches have restaurants, bars and other hospitality venues. They can be a major tourist attraction and a primary source of local income, especially in areas that are heavily influenced by commercial beach tourism industries.
In most places, the dominant feature of a beach is its sand, which may be comprised of fine grains of sand or rounded sand pebbles. Other beach materials include coral fragments and shells, and the skeletal remains of marine organisms that have washed ashore. Some beaches have a thick layer of compacted sand at their crest called a beach berm, with a thinner lower layer of looser material known as a beach slope or face.
During a storm, wave action carries sand from the surf zone (the area just in front of where the waves break) to the beach, depositing it as they recede. This process, called longshore drift, occurs on both coasts of the United States. The net movement of sand on American beaches is southward, because most of the large waves come from the North Pacific on the west coast and the North Atlantic on the east. In contrast, most of the sand moving up and down on Hawaiian beaches is northward. This is because Hawaii is closer to the source of the swells than is the United States.