Learning a new language is an activity that many people are interested in but which can prove to be a daunting undertaking. There are many apps that aim to teach languages, but it can be difficult to find particularly good apps that aren't expensive. One option is Mango Languages, but this is only available to those whose library subscribes to the service. For everyone else, Duolingo is a great option.
Duolingo offers lessons in German, French, Spanish, Italian, Portuguese and English. To test multiple language skills, lessons include a mix of reading, writing, translating, listening, and speaking exercises and gamify the entire language learning process to make it more fun. Give correct answers and you are rewarded with points, but if you make a mistake you will lose a heart; lose four hearts and you'll have to start the lesson over again. As you complete lessons, you not only unlock additional content, but you also earn skill points. If you have already studied a language, you can also test out of the early lessons to advance to those that will actually challenge you. You can also challenge yourself by racing against a clock or by competing against friends that you connect with through the app.
Duolingo has offered a free app for iPhones since last November and their free' Android app was recently released. In addition, Duolingo also offers a browser-based application for non-mobile devices and your progress will sync across all of your devices, so no matter where you are you can pick up where you last left off. If you want to practice a language you already know to keep up your skills or if you want to pick up a new language from scratch, Duolingo is a great resource!