In Safe Posture, NAO is stable, its motors and joints are safe. 

There are two Safe Postures for NAO : crouch or sitting :

Crouch posture

Sitting posture

NAO will go in Safe Posture (crouch) when:

• Turned OFF,
• In Rest mode.

You should always have NAO in Safe Posture when:

• You turn ON NAO,
• You want NAO to be still,
• You don’t use NAO.