HTC One M8 User Manual page 317

Make sure that the NFC area (shaded part) of HTC One and the
other phone's NFC area are close to one another. Experiment by
slightly moving the phones until a connection is made.
2. Tap the screen.
The shared content appears on the other screen. For some items that
you've shared (such as contact information), additional instructions on how
to save the item will appear on the receiving device.
Wireless sharing 317