The greenhouse effect is a natural phenomenon that warms the Earth’s surface. It occurs when greenhouse gases, such as carbon dioxide, methane, and water vapor, trap heat from the sun in the Earth's atmosphere. These gases allow sunlight to enter but prevent some of the heat that the Earth emits from escaping back into space. While this effect is crucial for maintaining a habitable climate, excessive greenhouse gas emissions due to human activities, such as burning fossil fuels, can enhance this effect, leading to global warming and resulting in significant environmental consequences.