 You're probably wondering how you go about putting programs on your computer. Well, first you should understand that there are a number of programs already included with Windows itself. These are programs which are installed by default when you install Windows. And they include a program called Notepad, which is just a very simple text editor. A text editor is like a word processor, but you can't do any sort of formatting with the text. You can't change fonts and you can't make things bold and so forth. It's basically just text without any formatting. Windows also installs a little calculator program, which you might find useful. Much more significantly, Windows includes Microsoft's web browser called Internet Explorer. And it also includes Microsoft's media player called Windows Media Player. And anytime in Windows, when you open a folder, a directory, the program which opens is called Windows Explorer, and it's an example of what's called a file browser. A file browser is just a program for looking through the directories on your system. It's arguable, however, if Windows Explorer is really a separate program, because it's more like something that's integrated into the interface of the operating system itself. In many ways, it just doesn't really act like a distinct program. In any case, those five are probably the most notable programs that come included with Windows. There are a dozen or so others, like, say, there's a free, solitary game, but most of them just aren't very interesting. As I have said before, web browsing takes up probably over 90% of what most users do with the computer these days. So if you're content using Internet Explorer as your web browser, then Windows pretty much has everything you need right there. However, if you wish to do more with your computer, then there are programs which you can buy to install on your system. For example, the most notable programs you might consider buying include Microsoft Word, which is Microsoft's word processor, Microsoft Excel, which is their spreadsheet, Microsoft PowerPoint, which is their slide presentation software, and Photoshop, which is made by Adobe and is an image editor. Photoshop actually comes in a couple different editions. There are two which are intended for actual graphic designers for professional level work, and those are very expensive. They're like at least $700 when you buy them. But there's a cheaper version meant for just casual home users called Photoshop Elements, and that's about $80. Microsoft Word, Excel, and PowerPoint are also quite expensive, however, they come in different versions. You can buy them individually, but usually people buy them together in a package called Microsoft Office. There's a cheaper version for casual users called Home and Student, and that's probably the one you want to buy. That's about $150, and that actually includes three different licenses, so you're actually allowed to install it on three different systems. If you're not interested in paying for software, there's plenty of stuff which you can legally download for free from the Internet. Notable examples include the Firefox web browser and the Google Chrome web browser. I strongly recommend using either of those browsers over in Internet Explorer. They're much better alternatives. There's a free alternative to Microsoft Office called Open Office, and it includes a word processor called Writer, a spreadsheet program called Calc, and a slide presentation program called Impress. And for image editing, there's a program called GIMP, which is an acronym standing for GNU Image Manipulation Program. And as a last example, while Windows Media Player is perfectly fine as a media player, you will find occasionally that there are some audio files or video files which you can't play back in Windows Media Player because it doesn't support those formats. So I recommend a free alternative called VLC, which has very broad support for all the formats out there. It plays pretty much anything. Now let's look at the files which make up a program. Files ending in .exe in Windows are called executable files, meaning they're files which can be executed. They can be run because they're actually pieces of code. So properly speaking, the executable file is the program itself. Files ending in the extension .dll are what are called dynamic linking libraries. They're files which contain code which executables can link to at runtime, meaning the executable can use that .dll as additional code. In practice, most programs don't put the entirety of their code into the executable file. They put some in some other .dll files. So the entirety of the code is spread among an executable file and some number of .dll files. The term resource file is simply a generic name for some file of data used by a program. Like for example, if a program has buttons with icons on those buttons, while those icons are images and they have to be stored somewhere. And so usually they're stored in separate files called resource files. Now it is possible to include data along with code in an executable file and some programs may do that, but generally that's considered a bad idea when a program has a lot of data. So usually programs will load their data from other files called resource files. Many programs have some number of options which the user can set. And so if the user sets these options, those options need to be stored somewhere. And so those configuration options are usually stored in what are called configuration files. So let's look at an example program. Here's this program which I downloaded from the internet called virtual dub. It's a video editing program. And what I downloaded from the internet was a zip file, a compressed archive. And when I uncompressed that archive, I got this directory. And inside the directory are all these files. So if you look here, you'll notice we have three executable files and we also have three DLL files. And in addition to that, we have a file-ending .chm, .jobs, and .vdi. Those last three are just some kind of resource files. It's data used by the program when it runs. Also in this directory we have two more subdirectories. If you look in there, you'll find additional DLL files. It's generally important not to move DLL files or resource files. Because when an executable runs, it generally expects to find these files in certain directories. And so if you were to move them, the executable would no longer know how to find them. This program is an example of the simplest sort of program to install. Because it's one where all we have to do to install it is simply unzip a zip file and then everything is in its place and we just run the executable file. Most programs these days can't be installed so simply, mainly because of this thing called the Windows Registry. The Windows Registry is a central registry in Windows for all sorts of configuration data, configuration data for all your programs, for Windows itself, and so forth. Most programs these days need to modify the Windows Registry when you install them, otherwise they won't run. You can't simply unzip the program files into a directory and then run the executable. That doesn't work for most programs. So that's one big reason most programs these days are installed not by just unzipping a zip file but by running an installer program. An installer program as the name implies is simply a program that installs another program. And this primarily consists of uncompressing the files and then putting them in all the proper directories and then doing whatever modification is necessary of configuration files and the Windows Registry. So here's an example. If I wish to install the Firefox web browser, I go to the Firefox website and I download this EXE file, this executable called Firefox Setup. Most installers in Windows are going to have the word setup in the name of the file. So when I run this installer, it first uncompresses all of the files, the executable itself contains all the compressed files, and then as is typical with installers, I'm presented with a window that's going to present me with some information and ask a few questions. So I click next here, it's asking me if I want to just go with the default options or whether I want to customize things a bit more. I'll go with the default options and hit next. It's then telling me which directory it's going to install Firefox in and it's asking me whether I want Firefox to act as the default web browser and this is the last question so the button doesn't say next, it says upgrade and I click upgrade. Firefox goes through with the installation and then when it's done, it tells me it's done and asks me if I want to launch Firefox right then and okay, that's fine. And Firefox is running and we're done. And that's a fairly typical installation process. Other programs are more complex or they're bigger, so they're going to take longer to install or they're going to ask you for more questions because they have more options but that gives you the basic idea. Now because program installation typically does more than just put some files in a certain directory, you shouldn't uninstall most programs just by deleting the directory they're contained in. Instead, if the program has an uninstaller program, you should use that uninstaller because the uninstaller program is going to effectively undo whatever was done by the installer program. Like say an uninstaller might undo some configuration that was done in the Windows registry. The place to go in Windows when you wish to run an uninstaller is this window in the control panel called programs and features. This window gives you a complete list of all the programs installed on your system and you can click on a program here and then hit the uninstall button and that will run the uninstaller for that program.