The greenhouse effect is the build-up of heat-trapping gases, such as carbon dioxide, methane, and water vapor, within the Earth's atmosphere, which acts like the glass roof of a greenhouse, allowing sunlight to enter and warm the planet but preventing some of the heat from escaping back into space. This natural process is essential for keeping the Earth's temperature at a level that can support life. However, the term 'greenhouse effect' is often used in the context of global warming to refer to an enhanced greenhouse effect resulting from the build-up of high concentrations of greenhouse gases due to human activities, primarily the burning of fossil fuels for energy, deforestation, and industrial processes. This increase in greenhouse gases traps more heat in the atmosphere, leading to a rise in the Earth's average temperature, a phenomenon known as global warming, which has significant implications for climate patterns, sea levels, and ecosystems worldwide.