Adding Authentication to Our App

We’ve made great progress so far, developing our to-do app and hosting it on the web. However, making our application available on the internet introduces a new problem: how do we keep our data safe? Anybody who knows the URL of our app can access it and can see all our to-dos. We need to add some kind of authentication to our app so that only authorized users can access it. In addition, wouldn’t it be nice if we could share our to-do app with our friends and family so they could also create their lists and keep track of their to-dos?

To achieve these outcomes, we need to add an authentication layer to our app. Authentication will ensure that only authorized users can see specific to-do items. In other words, before allowing users to create or edit to-do items, we will ask the users to authenticate themselves. If they are new to the website, they will be asked to register. If they are already registered, they will be able to use their...