Worldwide more human beings gain their livelihood from agriculture than any other endeavor; the majority are self-employed subsistence farmers living in the tropics]citation needed[. While growing food for local consumption is the core of tropical agriculture, cash crops (normally crops grown for export) are also included in the definition.
When people discuss the tropics, it is normal to use generalized labels to group together similar tropical areas. Common terms would include the humid-tropics (rainforests); the arid-tropics (deserts and dry areas); or monsoon zones (those areas that have well defined wet/dry seasons and experience monsoons). Such labeling is very useful when discussing agriculture, because what works in one area of the world will normally work in a similar area somewhere else, even if that area is on the opposite side of the globe.