The most obvious answer to this question is: because it makes your accounts more secure and it gives you the peace of mind you need.
What is two-factor or two-step authentication?
According to Wikipedia, two-factor authentication (TFA, T-FA or 2FA) is an approach to authentication which requires the presentation of two or more of the three authentication factors: a knowledge factor (“something the user knows“), a possession factor (“something the user has“), and an inherence factor (“something the user is“).
In more simple words:
- something the user knows is usually a username and a password
- something the user has is usually a mobile phone or unique token generator
- something the user is goes into the biometrical identification area (fingerprint scanner, retina scanner, etc.)
Two-factor authentication is not something new. It is there since many years, but until recently it was considered too complex for the “normal” Internet user. Now that more and more information and especially personal identifiable information is stored remotely on some servers in some country, also the need to protect it has become more stringent.
In principle it is very simple, but in the end it is up to the implementer how it is done, so there is no recipe that works for all services. Most of the services out there, Google, Facebook, Twitter and others have introduced it during year 2012.
It has two be done in maximum two steps. First thing is to configure your mobile phone, second, which depends on the type of the service, is to confirm which applications are allowed to access your account and in which way.
It might sound complicated, but remember that with more security the usability (how easy is to use the service) always suffers a little bit. The reward at the end is that you can sleep in peace that nobody will enter in your universe unless you want that.