Some people put their hands on their heads after Taslim (salutation of peace ending the Prayer), claiming it to be an act of Sunnah (action following the teachings of the Prophet).
It is not an act of Sunnah to put the hand on head after Taslim. In fact, this is a Bid`ah (innovation in religion). It is authentically reported that the Prophet (peace be upon him) said:
Anyone who does an action which is not in accordance with this matter of ours (Islam) will have it rejected.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.