The Greenhouse Effect is anprocess where Infrared (IR) rays from the sun come into the atmosphere. The atmosphere then traps these rays after they have come in (like the glass in a greenhouse). Green House gas are: CO2(carbon dioxide), N2O(nitrous oxide), and CH4(methane). For instance, on Earth, small amounts of carbon dioxide (CO2) in the air helps keep heat in the process of the Greenhouse Effect. As car exhausts and industries continue to shoot CO2 in the air, the amount of CO2 in the will increase. This causes more heat to be kept, increasing the Earth's temperature. Methane and Nitrous Oxide have the same effects as CO2, but they have a less harmful effect on the Greenhouse Effect. Viking Orbiter image showing the atmosphere of Mars above the Argyre Basin.
Source: NASA