This tutorial series is focused on building a custom Daily video call app with SvelteKit, specifically a chat sidebar feature that allows users to send and receive messages while participating in a call. The chat sidebar will display the participant's name and message text, as well as a form for submitting new messages. When a new message is received, it will trigger a notification system that displays a red notification when the chat is closed and clears when the chat is opened. The chat sidebar will also use Daily's sendAppMessage method to send messages and 'app-message' event to receive messages. The tutorial covers setting up the local environment, defining the chat feature, sending app messages, receiving 'app-message's, displaying chat messages, and displaying a notification system for new messages.