[MUSIC] Hi, and welcome back. In our last lesson, we talked about some of the details of a form submit button and why when we're doing client side only development, we can't really submit, a form just as we would when we have both a client side and server side. In this lesson, we're going to talk a little bit about the comparison of client and server side web development. So in this diagram, we have two computers on the left. One's a laptop, one is probably a representation of a desktop with a flat screen. When we're doing client side development, everything we do is actually staying on our computer. Let's say it's a laptop. When we do server side development, our code on the client side makes a request across the Internet to a server and that's the big box on the right. Now, we looked at GoDaddy a number of times when we were developing our site throughout this course. And GoDaddy is a server. They provide many servers to all of their many customers. So when a server receives a request, it returns usually a webpage to the client. Our work with HTML and JavaScript is staying completely on the client side in this course. So our pages aren't actually being submitted to the server. Now if you develop an attractive page and you deploy it to a host, for instance, GoDaddy, and make a request for that page using the URL, then you are requesting a page across the Internet. But our JavaScript examples in this course for validating forms are all happening on the client side. So another thing that happens on the server side, that part of the diagram on the right, is database access. Later, if you continue your career with web development, you'll probably be working with servers and with databases, as well as with clients. But in a course like this, it helps to do just one thing at a time and gain familiarity with things like HTML and JavaScript, before diving into what we call the full stack of development. And when we say stack, we're referring to client and server and database and also more detailed elements, arranged sort of conceptually as a stack of things. When we're working with a client side, we're working with a particular set of technologies and languages. So a client side element is the browser itself. And these are things, of course, like Chrome and Safari and Firefox and any other browser you might use. We work with HTML which we have done extensively in this course, CSS for styling our HTML, and JavaScript. All of these are elements of the client's side. On the server side, we have things like a web server, such as the one that GoDaddy provides for us, or any other hosting service. There are databases, which we haven't studied in this class, but most large web applications do have databases. For instance, consider where Amazon is keeping all the information about their books. PHP, which is a server side language. So for our course, our programming language is JavaScript. If you were doing a server side course, you might use PHP or you could also use Java or C#. And note here that while Java sounds like JavaScript, Java and JavaScript are completely different languages. Java is a server side language, and JavaScript, like in our course, is a client side language. C# is another language similar to Java and provided by Microsoft. So that's all for this lesson. Next time we'll be looking at some other elements of the JavaScript language, including loops.