Based on the text provided, Lipdub is an app available for download on the App Store for iPhone, iPad, and iPod touch. The app allows users to create lip sync videos by synchronizing their lip movements with pre-recorded audio tracks or songs. Lipdub provides a platform for users to express their creativity and create entertaining videos. Users can choose from a library of songs or import their own tracks to create personalized lip sync videos. The app also provides features such as video editing tools, filters, and special effects to enhance the videos. Additionally, Lipdub allows users to save and share their creations on social media platforms or with friends and family. The app has customer ratings and reviews available for users to read and compare before downloading. It is important to note that further information about the specific features and functionalities of Lipdub is not provided in the text.