Although your taskbar presents you with most of the applications currently running on your computer, there are dozens of processes running quietly in the background. Many of these are vital to Windows, and if they are turned off, your system will crash. However, some are unnecessarily wasting system resources, and others can be potentially malicious. Whatever the case, you may sometimes wish to see what programs are running in the background, and Windows makes this easy for you. However, to make smart choices about closing processes requires careful research.
Open Task Manager by pressing "Ctrl-Alt-Del." If you're unsure how to do this, simply hold down "Ctrl" and "Alt," which are on the bottom left-hand corner of your keyboard, and then press "Delete," which is found immediately above your arrow keys.
Click the "Applications" tab. Listed here are all applications running on your computer. Most of these will already be presented on your taskbar, but a number may be otherwise hidden. You can close them by first clicking on them and then choosing "End Task." In general, closing applications will not crash your system. However, if you're unfamiliar with an application, first look it up on a search engine.
Click the "Processes" tab. Listed here are the processes running in the background of your computer. Many of these are essential for Windows to operate, but a handful can be safely closed by first clicking on them and then choosing "End Task." As with unfamiliar applications, be sure to research a process before closing it.