Hajj is one of the best forms of worship and one of the most sublime deeds because it’s one of the pillars of Islam. A Muslim’s religion is incomplete without it. (Any) worship is only acceptable when the following is true:
One devotes it to Allah alone, with a desire for the Hereafter. It cannot be done with the intention of being seen among people or for worldly gain.
One follows the Prophet’s example, in words and deeds. This cannot be accomplished except by gaining knowledge of the Sunnah.
The three types of Hajj:
Tamattu: A pilgrim wears Ihram for Umrah only during the months of Hajj, which means when a pilgrim reaches Makkah, he/she makes Tawaf and Sa’i for Umrah. Then shaves or clips the hair. On the day of Tarwiya, which is the eighth of Dhul Hijja, the pilgrim puts on his Ihram for Hajj only and carries out all of its requirements.
Ifrad: A pilgrim wears Ihram for Hajj only. When he reaches Makkah, he performs Tawaf for his arrival and Sa’i for Hajj. He doesn’t shave or clip his hair as he doesn’t disengage from Ihram. Instead, he remains in Ihram till after he stones Jamrah Al-Aqaba on the Eid day. It is permissible for him to postpone his Sa’i for Hajj until after his Tawaf for Hajj.
Qiran: A pilgrim wears Ihram for both Umrah and Hajj or he wears Ihram first for Umrah, then makes intentions for Hajj before his Tawaf for Hajj. The obligations on one performing Ifrad are the same as those on one performing Qiran, except that the latter must slaughter whereas the former is not obligated to do so.
The best of the three forms is Tamattu. It is the form that the Prophet (peace be upon him) encouraged his followers to perform. Even if a pilgrim makes his intention to perform Qiran or Ifrad he is allowed to change his intention to Tamattu. He can do this even after he has performed Tawaf and Sa’i.
When the Prophet (peace be upon him) performed Tawaf and Sa’i during the year of the Farewell Hajj with his Companions, he ordered all those who hadn’t brought sacrificial animals to change their intention for Hajj into intention for Umrah. cut their hair, and disengage from Ihram till Hajj. He said, “If I hadn’t brought the sacrificial animal, I would have done what I have ordered you to do.”
– By Sheikh Muhammad Bin Saleh Al-Uthaymeen
– Excerpt from the book How to Perform the Rituals of Hajj and Umrah