A Digital ID, sometimes called a digital certificate, is a file on your computer that identifies who you are. Some software applications use this file to prove your identity to another person or computer. Here are two common examples:

• When you bank online, your bank must be sure that you are the correct person to get account information. Like a driver's license or passport, a Digital ID confirms your identity to the online bank.
• When you send important e-mail to someone, your e-mail application can use your Digital ID to "digitally" sign the e-mail message. A digital signature does two things: it lets the recipient know the e-mail is from you, and it tells them the e-mail was not tampered with from the time you sent it to the time they received it.