public wifi

It is possible that some people use cheap laptops to use only for connecting to publc wifi network connections, and public internet connections which they don't subscribe to or own because they don't trust the internet connection or wifi router at a public place is safe to connect their more...

I think your data would be safer from hackers if you use the library/school computer to just read blogs, and websites which don't require you to make a username and password to login to read articles, or watch online videos. But, it would not be a good idea to plug in a USB drive into a computer...