When I was 16, I spent a summer studying Spanish in Spain. Armed with a pocket-sized Spanish-English electronic dictionary—high-tech at the time— I stumbled through the country.

Now language translation apps for smartphones can do much, much more than that old plastic device with the rubbery buttons and one-line display. Many of them let you speak or type a question in English and have that instantly translated into a foreign tongue, which the app can speak out loud or display on the phone’s screen. A response from a local can be translated right back into English for you.