The Lighthouse is atypical visual aid，attracting the visual sense of the navigator．
Each visual aid may be recognized by the color of the light and light rhythm（characteristic of the light）at night，and the structure of the tower，the shape and color during the daytime．
The electric power supply depends mainly on the commercial power supply，but solar power generators，wind activated generators，wave activated generators，diesel generators and air cell batteries are also used as the source of power for aids to navigation．

Lighthouses

Coastal lighthouses are erected on cliffs or outstanding locations to serve as landmarks for vessels to determine the site location and the position of the vessel．
The tower is usually painted white，but on islands far from the mainland or in locations with deep snow，the towers are sometimes painted in black and white or red and white stripes．
Lighthouses built on breakwaters in commercial ports and fishing ports are called “breakwater lighthouses．”
The lighthouse on the left side facing the inner port （port hand）is painted white, while the lighthouse on the right side （starboard　hand）is painted red．
The port hand light is of a green or white color while the starboard hand light is of a red color．

Off Shore Fixed Lights

Off shore fixed lights are located on shoals and reefs to indicate the existence of dangerous obstacles near the navigating routes．
Off shore fixed lights may be divided in to 4 types according to the location．

●Isolated Danger Marks

The structure is painted black with red stripes．
The color of the light is white.
As a top mark，two round black balls are Placed at the top．
The light indicates that an obstacle exists on the spot or neighboring waters．

●Port Hand Marks

The structure is painted green and the light is of green color．
The top mark is of a single green cylinder type．
The light indicates that an obstacle exists on the left side of the light．
Incoming vessels will proceed watching the light on the port hand．

●Starboard Hand Marks

The structure is painted red，and the color of the light is also red.
The top is of a single red cylinder type.
The light indicates the existence of an obstacle on the right side．
Incoming vessels will proceed watching the light on the starboard hand．

●Cardinal Marks

The marks are painted yellow with black horizontal belts．
Depending on the painting of the belt，the channel exists on either the east，west，south or north direction，indicating the existence of obstacles on the opposite side．
The top mark consists of two black cylinder marks，and as in the case of the color of the paint, different combinations of top marks indicate different situations．
The light is of white color，but by changing the characteristics of the color, the same purpose may be obtained as in the case of the color and the top mark．
The color and light characteristics of off shore fixed lights are determined by a common rule throughout the world（the IALA Maritime Buoyage System）．
IALA stands for the international Association of Marine Aids to Navigation and Lighthouse Authorities．

Lighted Buoys

Lighted buoys are floating in the sea at the entrance of a fixed channel，the middle of the channel，the left and right limits of the channel and the turning points．
The buoys also indicate reefs，shoals and other dangerous obstacles near the channel．
The buoy body on the sea surface is linked to a sinker at the sea bottom by a chain.　
According to the purpose of installing lighted buoys，the color of the buoy and light characteristics are determined in accordance with the IALA Maritime Buoyage System as in the case of fixed lights．
The buoy indicating the center of the channel is called the Safe Water mark．
The body is painted in red and white vertical stripes, the color of the light is white, and the top mark is of a single red cylinder type．
The safe water mark is installed in areas without obstacles in the neighboring waters.

Projector

From a tower erected on a nearby cliff，a light of strong intensity is projected on obstacles to inform vessels of the existence of the obstacles．
In some cases，a pole is erected on the obstacle to be projected to achieve favorable effects．

Leading Lights

In difficult channels，and harbors with a narrow entrance，in a site on land in the extension line of the navigating route，a front light of a lower altitude and a rear light of a higher altitude are erected．
Vessels may find a safe navigating route by watching the two lights so that they will fall into a straight line．
In the daytime the vessels watch the triangular top of the poles，but in some places，even in the daytime the light is turned on for the safety of navigation．

Sector Lights

By projecting lights of three different colors，a single sector light serves the same purpose as the leading lights．
From the vessels，the dangerous spot on the left side is indicated by a green light，and the dangerous spot on the right side is indicated by a red light，and the vessels may navigate in the safe zone of white color．
At places，strong lights are turned on during the daytime as well to secure the safety of navigation．