Two-Factor Authentication is `Some thing you know` and `Something you have` and in the case of Duo Something you have would be your smart phone and in Duo you will have different ways of doing this but in all of them you first enter username and password which is `what you know` and then one of the following:
- Phone callback
- In this form the system will call you and then you can simply enter the pin that system is telling you and you are logged in like PayPal Verification program by phone for your address.
- SMS-delivered one-time passcodes
- You will recieve a SMS on your phone and then type in the passcode.
- Duo mobile app to generate one-time passcodes
- App will make the code you just have to type it in.
- Duo mobile app for smartphone push authentication
- So all you have to do is to accept on your phone and you are logged in.
- Duo hardware token to generate one-time passcodes
- And it will send it to you to type it in
And the best part is that it is free for the first 10 employee on your account and after that its $3 per month but if you are making a system that you want it to be secure like a wordpress blog that you dont want everyone hack into and you are the only person or you have two other people who will write to the system then use it it will give you much easier sleep at night!