Welcome to lesson four. Lesson four is all about authentication. This is one of my favorite lessons, actually. We’re going to build a complete log in system, or learn how to build a complete log in system rather. And then you’re going to build a complete log in system for your blog. So users can actually log in and register on the blog that you’ve been working on so far. We’re going to learn about cookies, which is a little bit of information your browser stores to know what user is logged into your blog. We’re going to talk about passwords, an hashing passwords, an how to store those securely in your database. An we’ll also just talk about hashing in general, because it’s a really handy little tool that’ll come up, many times throughout your, programming career. It sounds simple but it’s actually quite complex. It’ll be a lot a fun. So, let’s get started.