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.
If you are on a certain data plan on your mobile provider, and don't want to exceed it, you can set data usage warning and a limit which can help you save some of your money.
If you are getting a vast number of email notifications sent by your Twitter account and they started to annoy you, this is how you disable and manage them.
You add a hashtag to your uploaded Instagram pictures but when you click the hashtag your picture doesn't show up there? Yes I know, it's pretty frustrating, but I happen to know how to fix this!