Why green and red lights?

Originally taken from the marine world. Green means go, Red means stop. Similar to a boat's bow lights. When you see green, you are the "privileged" vessel (aircraft, etc.) and may proceed. If you see red, you are the "burdened" vessel and must give way and let the privileged vessel proceed on it's course. Also notice that the lights at the rear of the plane are white, just like a boat's stern or mast light.

In 1848 the United Kingdom passed regulations that required steam vessels to display red and green sidelights as well as a white masthead light. In 1849 the U.S. Congress extended the light requirements to sailing vessels. In 1889 the United States convened the first International Maritime Conference to consider regulations for preventing collisions. The resulting Washington Conference Rules were adopted by the U.S in 1890 and became effective internationally in 1897.

This is standard navigation / position lighting, for the red light to be on the left and the green light to be on the right. It is derived from marine navigation rules. If you see an aircraft at night you can use the location of the lights to determine what direction the aircraft is moving (i.e., is it moving toward you or away from you).

Same as for boats and ships... red on the port (left) side, green on the starboard (right) side. A white light is affixed to the stern of a boat, and on the tail (or other aft facing structure) of the airplane.

The lights are designed to be directional, such that if you see both red and green lights, the airplane is coming toward you. If you see green only, you are on the right side of the aircraft, and if you see white only, you are behind the airplane

You can remember which is which a couple of ways:

1) "red" and "port" have fewer letters than "green" and "starboard"

2) port wine is red, therefore the port light is red, leaving the starboard light to be green.

All the maritime answers are right, it's a holdover. The rest are why you should never do your homework here.

I believe it comes from shipping navigation.

Green means correct, calm, safe, good, go

Red means wrong, danger, stop

Because green means go and red means stop.

Red is a really eye catching color and green is calm.