Zip files are compressed archives containing documents, images, folders, basically any type of files on your computer. We create them to save space and make them more practical for sending via email or file sharing services.
You have more people using one computer and you don't want them to be able to shut it down using a shutdown button on Windows logon screen, this is how you remove it.
Some installations or settings changes require you to restart your computer. In most cases you don't need to actually reboot it, you only need to restart the explorer.exe process.
