As our world continues to globalize, the need for communicating in more than one language ever increases. Spanish, Mandarin [Chinese], and English are the world's most useful languages to know. Learning a foreign language can also keep your brain sharp as you age and some people count it as a hobby. So whether you do it for business or pleasure, you can be sure to expect a decent return on investment. Now go study a new language! Buena Suerte!