Since your PayPal account may be linked to a checking account, debit card, or credit card, you really need to have as much security surrounding your account as possible. If you do any business via PayPal or eBay, you should look into making this small investment to protect your information and money.
Once your PayPal security key arrives in the mail, you'll need it every single time you logon to PayPal. You can still logon on from any computer, but you'll need to have your user name, your password, plus a special 6-digit security code that is displayed on your personal key. This code changes every 30 seconds to protect your account from hackers. The security key comes with a little jump ring so you can attach it to your keychain, if desired.