Always notify user. 

When user performs an action always make sure he is getting the enough information what is is going on.

Example 1:

User should always aware of what is going on. Modern front end technologies use MVC frameworks which always fail to notify user.

Example 2:

Always show progress bar or loading status if we want user to wait for something.

Show user their footprints.

Showing breadcrumbs is always a better idea

• If your website has lot of pages including nested categories.
• If user is not on mobile device
• If user is working with forms and there are lot of steps in filling the form.
• If you have e-commerce website

That way user will never get lost.