Window.localstorage stores data with no expiration date. The Web Storage API provides a mechanism by which browsers can securely store key / value pairs in a more intuitive way than by using cookies. Calling it will create a new instance of the Storage object so that individual items can be retrieved, deleted and set. LocalStorage is better than sessionStorage - while you need to know that both can be deleted by the user, you shouldn't rely on data persistence for both.