A digital sticky notes app is built using Flask for the backend API, JavaScript, and Svelte for the UI, with Twilio Sync to store the notes. The application allows users to create new sticky notes, drag and drop them on the screen, and delete them. The user interface is built using Svelte components, including a Wall component that displays the sticky notes and a StickyNote component that represents each note. The application uses environment variables for authentication with Twilio Sync and stores the notes in a sync list. The app can be tested by navigating to http://localhost:5000/ and interacting with it.