So, welcome to JavaScript, jQuery and JSON. This is the fourth class that we're teaching. And at the end of the previous class, you sort of worked on a CRUD application which really made it so that you connected PHP to the database in a user interface. And we introduced the concept of the model-view-controller, where the model is the database, the view is what the user sees, and the controllers, sort of the magic that shuffles things back and forth, and redirects the user and all that stuff. And so, in this class, what we're really doing is what the industry and web applications is doing, and that's playing with how we partition the model-view-controller across the browser, the server, and the database. Everything you've done so far is rendered HTML in PHP. That's the simple thing. And what we're going to explore in this class, is moving some of the rendering of the HTML from the PHP into the browser. So, we're going to learn JavaScript, okay. And so, building that HTML mark up and sending to the browser's old school and it's something you should know how to do. But, to be cool and to be interactive and dynamic, to build little chats, the little red things that pop up without having to do full page refreshes, that takes interactivity, and that takes JavaScript, and that takes jQuery. And so, if you will build a chat application and you'll realize that, oh, that chat window can sort of go off in the background, get a new chat, and it just shows up in the window. And so, all this stuff where you don't have to do full request-response cycles and we can repaint parts of web pages that repaint the whole web pages, that's the kind of thing we're going to learn. And that's kind of the fun aspect of modern web applications. So, we need to learn JavaScript, jQuery, which is a JavaScript library that helps talking to the document object model and sending that back and forth, and JSON, which is a format that we can cause JavaScript to actually read data from the database and then format it inside the browser. So, we're going to do all kinds of cool things. And that's how we're going to accomplish all these more interactive user interactions. This course is probably a little more challenging than the other courses that we've done so far. Just because you better know what you're doing, and it's like, here's some JavaScript and boy, we're going to do this stuff, and now you got to change the DOM, and we move pretty quickly through each of the assignments and the assignments are a little longer. So, be ready to spend a little bit more time working on this course, be building slightly larger applications. But, this is where you sort of move into a situation where you're going to be able to walk into someone doing web development, or an organization do web development, you're going to know the stuff that's in this. You need to know the stuff that's in this class to sort of consider yourself a modern web developer. So, invest a little more time, I think it's worth it and if you got this far and you've made it through those first three classes, I'm proud of you, and I'm glad that you're still interested, and we'll see at the end of this one, because at the end of this one, you're going to know a whole lot of stuff.