Hello there, eager learner! Today's programming adventure takes us into the deep world of back-end engineering. Specifically, we will focus on handling HTTP status errors 404 and 500 using Express.js.

In the world of the web, errors are unavoidable. Every time you've come across a page that says "Page Not Found" or "An unexpected error occurred" you've encountered a 404 or 500 error, respectively. Being able to handle these errors gracefully is a key skill for any web developer.

You'll learn how to customize how your web application responds to these errors. By the end of this lesson, you'll have the tools to not only understand these errors but also guide your users with useful error pages. Effective error handling enhances user experience and strengthens your application.

Driving on the highway of the internet, whenever there's a hitch, HTTP status codes serve as our mile markers. Two frequent ones we encounter are 404: "Not Found" and 500: "Internal Server Error."

A 404 error means the browser requested a page that doesn't exist on the server. For instance, if you type www.notarealwebpagename.com into your browser, there's no page with that name, so you would get a 404 error!