Emotion detection (emotion recognition) is the task of classifying emotions, such as joy, anger, sadness, or surprise. For example, trained ML algorithms can identify happiness (and its magnitude) from an image of a smiling face. Other algorithms are able to characterize the sentiments of a speaker from an audio recording. Emotion recognition has a wide range of applications, from patient care in diagnosing mental disorders by voice analysis, to retail, where computer vision-equipped cameras would track people’s reactions to new articles.