What are greenhouse gases, and why do we say the greenhouse effect is a good thing?

Greenhouse gases, such as water vapor (H2O), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), are present in Earth's atmosphere and help to absorb, trap, and re-emit heat (infrared radiation), thereby warming the Earth's surface. The greenhouse effect, which is the process of these gases absorbing and re-emitting infrared radiation, is considered a good thing because it helps to maintain Earth's average temperature, supporting the survival of various life forms and promoting ecosystem preservation, biodiversity, and agricultural production. However, it is crucial to differentiate between the natural greenhouse effect, which is necessary for life, and the enhanced greenhouse effect caused by human activities, such as burning fossil fuels, deforestation, and industrial processes, which leads to accelerated warming of Earth's climate and can have adverse effects on ecosystems, weather patterns, and sea levels.