Redux state is useful for when other parts of the app need to be aware of or react to that state.<p>Sometimes there are little bits and pieces that may look like they are "private state of a component" but over time you'll find instances where it's useful to know that state.<p>For example I have a LoginForm component and a SignupForm component.<p>If you have half-way filled email and password on the LoginForm, but click on "Create an account" it would be nice if SignupForm picked up that state from the login form.<p>So my LoginForm state is stored in the redux store under the key "loginForm".<p>And SignupForm will pick up that state if available and vice-versa for going from sign up to log in.
What I like to do is not use Redux at all until I find I need it. So basically it comes a point in my app when I have too much information in my state and I need to share it with multiple components. At this point, I add the most global stuff to the redux store and keep meaningless things as react state.
Use Redux state if you want the data to be available across multiple components.<p>Use React Component State if no other component cares about the data.