Aids to Navigation (ATONs or AtoN) are external devices—including buoys, beacons, lights, and electronic signals—used to help sailors determine their position, determine a safe course, or warn them of hazards. They act as road signs on the water, highlighting channels, obstructions, and safe passing areas.

Key Aspects of Aids to Navigation:
Types: They can be floating (buoys) or fixed (beacons, lighthouses).

Systems: The two main systems are the Lateral System (which marks channel sides using colors, shapes, and numbers) and the Cardinal System (which marks hazards based on compass direction).

Lateral Markers (US): Follow the phrase "Red Right Returning" when entering from seaward; red, even-numbered markers stay on the starboard (right) side, and green, odd-numbered markers stay on the port (left) side.

Identification: They are identified by their color (e.g., green/red), shape (e.g., nun/can buoys), light characteristics (e.g., flashing, occulting), and numbers.

Purpose: They improve safety by providing precise positioning information for sailors.