The most widely spoken language on the planet is based in the most populated country on the planet, China. Beating second-place English by a two to one ratio, but do not let that lull you into thinking that Mandarin is easy to learn. Speaking Mandarin can be really tough, because each word can be pronounced in four ways (or "tones"), and a beginner will invariably have trouble distinguishing one tone from another. But if over a billion people could do it, so could you.