Rene wants to know if she can use a VPN to keep herself safe and still log into sites like Facebook. Leo says that a VPN is an encrypted tunnel for your traffic that masks your data as you use it. You should be able to still log in, but some sites don't support it. How about using an airport WiFi with a VPN. Leo says that's a very good place to use a VPN, but he generally doesn't use public wifi, especially in an airport. And you NEVER want to do banking or eCommerce on one.
The good news is, that Google is making websites move to encryption, so when you log in, all your traffic is encrypted. So most people don't really need to use a VPN. But if you use one, don't use a free one, chances are, they're selling your traffic to make money.