The greenhouse effect is the trapping of the sun’s heat in the atmosphere of a planet by gases in that atmosphere. It’s called the greenhouse effect because it has a lot in common with how the glass of a greenhouse traps heat inside: heat can get into the greenhouse, but has more trouble leaving.
The greenhouse effect happens because of so-called greenhouse gases, which include carbon dioxide, methane, water vapor, and others. The biggest components of the atmosphere, nitrogen and oxygen, are not greenhouses gases. More details HERE.
Earth Blanket Effect would be more accurate but, because ‘greenhouse effect’ has been used so long and is so ubiquitous, I include it in this glossary. More details HERE.