When working with structured data like arrays or objects in localStorage, you cannot store them directly because localStorage only accepts strings. To handle this, you use JSON.stringify to convert your array of objects into a string before saving. When you want to retrieve the data and use it as an array of objects again, you use JSON.parse to convert the string back into its original structure. In the example above, every time the to-do list is saved, JSON.stringify turns the array of objects into a string for storage. When loading the to-do list, JSON.parse is used to turn the string back into an array of objects, allowing you to easily add or remove items and update the UI.