Lighthouses are towers, buildings, or other physical structures designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. They mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors, and they also assist in aerial navigation. Here are some key points about lighthouses:

• Lighthouses warn mariners of dangerous shallows and perilous rocky coasts, and they help guide vessels safely into and out of harbors.
• Lighthouses come in all shapes and sizes, but they all have a beacon (light) at the top, which is housed in a room with large windows all around called a lantern room that is topped with a domed roof called a cupola.
• Most lighthouses also feature a few rooms near the top, such as a service room used to store cleaning and maintenance supplies, and a watch room that serves as a place for the keeper to keep watch from at night when the beacon is lit.
• Lighthouses are painted differently to help mariners identify them during the day. For example, a lighthouse may be painted all white if its surroundings/background is dark. The red and white stripes help the mariner identify the lighthouse if it’s up against a white background, such as cliffs or rocks.
• The height of a lighthouse takes into account the curvature of the earth, so the higher light above MHW (mean high water), the further away it can be seen at sea. But the light should not be so high up that local sailors will not see it. This is why you will frequently get shorter lighthouses on the top of cliffs and taller lighthouses built nearer the water surface.
• Lighthouses are still in use today, although many have been replaced with automated systems or decommissioned due to changing navigation needs. Nevertheless, lighthouses remain an iconic symbol of guidance, safety, and security.

In summary, lighthouses serve as navigational aids and warn boats of dangerous areas. They are designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. They mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors, and they also assist in aerial navigation. Although they are now considered old-fashioned and obsolete, lighthouses continue to serve as symbols of hope to this day.