If this is a household circuit, the red wire is usually a traveler between three way switches. Ground is almost always bare copper, sometimes with green insulation, and sometimes with green and yellow striped insulation.
only for USA, Canada and countries using similar 60Hz household electricity supplies.
Red and black are the two separate 120V hot legs of a 240V 60Hz supply, green is the ground. White is the...
Red, white, and black are standard for a three-way switch (you have two switches that control the same fixture). You should also have a ground wire (copper, unsheathed). The black and red are...