What are artificial headlands built parallel to the coast called?

The correct term for artificial headlands that are constructed parallel to the coast is "Offshore headland." These structures are designed to protect the coastline from erosion and to create calm water areas for activities such as fishing or recreation. They can also help to manage sediment transport along the shore, which is crucial in maintaining the balance of coastal ecosystems.

The other concepts mentioned do not refer to structures built parallel to the coast specifically to protect or influence shorelines in the same manner. Rip rap consists of large stones or boulders placed along the coastline to absorb wave energy and reduce erosion, but it does not fully resemble an artificial headland in design and function. Coastal sand dunes are natural formations that provide some protection against erosion and serve as a habitat, but they are not built structures. Tide refers to the periodic rise and fall of sea levels caused by gravitational interactions between the Earth, moon, and sun and does not pertain to coastal structures at all.