热带是地球上南、北回归线（南、北纬23度26分）之间的地区的总称，无极昼极夜现象。

热带有时从气候上定义，指最冷月均温在18摄氏度以上的地区。热带的两边是亚热带。一些研究显示，气候热带的范围正在变宽。气象学家猜测主要影响因素可能是全球变暖、臭氧层损耗、厄尔尼诺现象以及太平洋海域的定期天气现象等。

热带气候区大多地处低纬，故终年高温，气温年较差日较差均较小，但其内部不同地区降水差异很大。按周淑贞气候分类法，气候类型有赤道多雨气候、热带海洋性气候、热带干湿季气候、热带干旱半干旱气候和热带季风气候等。

The tropics are a region of the Earth surrounding the Equator. They are delimited in latitude by the Tropic of Cancer in the Northern Hemisphere at 23°26′13.8″ (or 23.43717°) N and the Tropic of Capricorn in the Southern Hemisphere at 23°26′13.8″ (or 23.43717°) S; these latitudes correspond to the axial tilt of the Earth. The tropics are also referred to as the tropical zone and the torrid zone (see geographical zone). The tropics include all the areas on the Earth where the Sun reaches a subsolar point, a point directly overhead at least once during the solar year.