What is NFC, how and where can I use it?

Near Field Communication (NFC) allows for wireless, rapid pairing and connecting with other NFC-enabled devices, without having to enter passcodes and confirmations.  Some examples are: launch web content by touching an NFC tag with your phone, use convenient contactless payment or ticketing systems (depending on region), or touch your friend's NFC-enabled phone with your phone to copy a picture directly, or play a game optimised for NFC.