What is the Greenhouse Effect?

The 'greenhouse effect' is an atmospheric heating phenomenon in which the Earth experiences rise in temperature because certain gases (water vapor, carbon dioxide, nitrous oxide, and methane) in the atmosphere allow incoming sunlight to pass through but trap heat radiated from the earth's surface. If these gases wouldn't trap heat in the atmosphere, the temperature of the earth would be about 33 degrees centigrade colder on average. Because how these gases warm our planet, they are called as greenhouse gases and the effect they create in the atmosphere is called as greenhouse effect.