Welcome to the final course of the series. In this course, you learn how to extend Python with code that someone else has written and made available on the internet. One of the reasons Python is so popular is because many developers from around the world have written great code and shared that code freely online. And this lets you build on other's work, and it can make the process of writing your own code much faster. Python has tools available that lets you download and install code written by many others. This third party code is usually bundled together into something called a package, and you learn how to install Python packages, which can immediately give you additional powerful functions to call. For example, if you want your code to download a web page and extract a text and maybe summarize the text for you, you'll be able to find a free package that lets your code download and extract text. This is something you see later in this course, and will go over a lot of examples of the types of things you better get packages to do for you. So far, I've spoken a little bit about packages that let you install code that runs on your computer, but one important type of package goes further and provides application programming interfaces or APIs that lets your code call on someone else's code running on someone else's computer on the internet. For example, their API lets your computer go online and ask some other computer, say run by a weather service, to return the current weather at this moment in time in a given location. There are also APIs that you could go online and get the current news, or get stock prices, or even search the web. In addition to using APIs to gather information, code can also use APIs to even take action in the world, such as, maybe have your code use an API to send a text or email message that will land in someone else's phone, or even use an API to place an online shopping order that results in a physical product being shipped to someone's house. In programming, building on each other's work has always been a key part of how we can get so much done. It is by standing on the shoulders of giants, using other's code and much more that lets us all write code much faster and more effectively. And now, with the availability of AI chatbots, you can also get advice on what popular packages or APIs might be suitable for your project, and also have a chatbot help you write code to use these packages or APIs. On this website, we'll make many tools, packages, and APIs available to you and also show you how you can install additional packages onto your own computer. So, this course will significantly expand what your computer can do. Let's get started by looking at what the import command, which you've already seen in previous courses, is actually doing, and how the import command lets you load someone else's code. Let's go see that in the next video.