What "greenhouse" means in gardening

A greenhouse is a structure, often made of glass or plastic, that is designed to control and maintain the environment for growing plants. The controlled environment can help extend the growing season, protect plants from pests and weather, and provide ideal conditions for seed germination, propagation, and cultivation. Greenhouses may also have heating and cooling systems, irrigation, and ventilation to regulate temperature, humidity, and air circulation. They can be used for a variety of gardening activities, such as growing vegetables, herbs, flowers, and exotic plants.