Final answer:
The greenhouse effect is the trapping of energy, specifically thermal energy, by greenhouse gases in the atmosphere, which prevents it from escaping Earth, thus contributing to global warming.
Step-by-step explanation:
The phenomenon that occurs when energy is trapped and held by a surface rather than passing through or reflecting off it is known as the greenhouse effect. Substances can act as reservoirs of energy by storing the kinetic energy of their atoms or molecules in various motions such as translations, vibrations, or rotations. The greenhouse effect specifically refers to the trapping of long wave infrared radiation (thermal energy) radiated by Earth, which is absorbed by greenhouse gases in the atmosphere, preventing it from escaping and thus contributing to the warming of the planet.