A simple to-do list is a web application built using HTML, CSS, and JavaScript that allows users to create, manage, and track their tasks or to-do items. It typically features an input field for adding tasks, a list to display the tasks, and options to mark tasks as complete or delete them. CSS is used to style the interface, making it visually appealing, and JavaScript handles the logic, such as adding, updating, and removing tasks, as well as managing their completion status. Users can interact with the to-do list by entering task descriptions and using buttons to mark tasks as done or delete them. This basic web application is an excellent introduction to web development and demonstrates how these three technologies work together to create a functional user interface.