Operating system (linux/unix/windows/mac, generally used for applications)
Browser (it's firefox/ie6/ie7/ie8/, generally used for web pages)
Shell (powershell/Cygwin/bashshell/cmd/bourne shell, commonly used in scripting languages).
Hardware (such as cpu/ram/ hard disk, usually hardware)
Wait a minute.
I hope I can help you. If you have any questions, please leave a message.