In order to work, an application usually has to be installed on your computer. Typically, installation is as simple as inserting the installation disc and following the instructions on the screen. For software downloaded from the Internet, you can usually double-click it after it is finished downloading and then follow the instructions on the screen. Many applications include a readme file (for example, readme.txt), which includes installation instructions and other information. Use caution when downloading software because it can contain viruses or other malware. If you have an antivirus program, you should scan the downloaded software before installing it.
Files and applications
Each application on your computer has a group of file types—or formats—it is able to open. You generally won’t have to figure out which application will open your files. When you double-click a file, your computer will automatically use the correct application to open it, as long as the application is installed on your computer.
If you don’t have the correct application installed, you may not be able to open the file. However, in some cases you can open the file with a web application that runs in your browser. If you’re not sure what a file’s format is, you can look at the extension at the end of the file name (such as.docx, .txt, or .jpg).