Canon EOS 6D Instruction Manual page 108

Using AF to Focus (AF Method)
108
Focus the subject.
2
Press the shutter button halfway and
the camera will focus the face
covered by the <p> frame.
When focus is achieved, the AF point
will turn green and the beeper will
sound.
If focus is not achieved, the AF point
will turn orange.
If a face cannot be detected, the AF
point < > will be displayed and AF
will be executed at the center.
Take the picture.
3
Check the focus and exposure, then
press the shutter button completely to
take the picture (p.104).