In a previous post, I wrote about password managers and why you should have one, In this follow up article I'll try to explain Two Factor Authentication or 2FA and how it can make your security more robust.
So what 2FA does is that It adds another layer to your security.
After you provide your username and password 2FA will ask for a special code that you may receive via SMS or an authenticator app. You can only login after providing the 2FA code.
So now, even if someone manages to get their hands on your login credentials they still won't be able to access your account. 2FA is not unbreakable but it is more secure than passwords.
Most of the online services provide 2FA including Google, Facebook, Twitter, GitHub, Steam etc. You can setup 2FA for your account by going to the security settings of that platform. You can also visit twofactorauth to check if a service provides 2FA or not.
For authentication you may use SMS or an authenticator app.
Using an authenticator app is recommended though as it can backup your codes and sync them across multiple devices, so even if you happen to lose your primary device or SIM card you'll still be able to access your accounts without any problems.
A good cross platform authenticator app is Authy. It has all the standard features of an authenticator app plus backups and support for multiple devices.
I hope you now have a basic understanding of what 2FA is and will be using it to lockdown your online security.