UTAU is a free software application that allows users to create singing voice synthesizers. It was developed in Japan and enables users to input lyrics and melodies, which the software then converts into sung audio using voice banks. These voice banks can be created by recording a person's voice or can be downloaded from various online sources. The software is popular among music producers and hobbyists, particularly in the Vocaloid community. Users can customize their voice banks and create unique characters, often leading to a vibrant culture of original songs and fan-made content.