Umrah is: Ihrām, Tawāf, Sa’ee, shaving or shortening the hair.
As for Ihrām then it is the intention to enter into the ritual of umrah (or hajj) and to dress accordingly for that. The Sunnah for the one who intends umrah is that he makes ghusl as he would from sexual impurity (janābah), and then to perfume himself with the best perfume he can get hold of such as ‘Oud (aloeswood or agarwood) or something similar; applied to his head and beard. Any remnant of that perfume that remains upon the person does not harm after he enters into Ihrām as occurs in the two Saheehs from the hadeeth of Ā’ishah (May Allah be pleased with her) that she said:
“When Allah’s Messenger (salallaahu ‘alaihi wassallam) would wish to enter into Ihrām he would apply whatever perfume that he could find. Then I would see the glistening of the musk in his head and beard thereafter.”
Performing ghusl at the time of entering Ihrām is a Sunnah for both men and women, and even the menstruating and post natal bleeding women. This is because Allah’s Messenger (salallaahu ‘alaihi wassallam) commanded Asmā bint ‘Umais with it after she had given birth to Muhammad Ibn Abee Bakr at Dhul-Hulaifah (which is meeqāt for the people of Madinah) as they were embarking on the farewell Hajj. So he said to her:
“Perform ghusl; and bind yourself (i.e. the private parts) with a cloth and enter into Ihrām.” Reported by Muslim from Jābir (radiyallaahu ‘anhu).
See ‘Allāmah, Ibn Uthaimīn (rahimahullāh): Manāsik al-Hajj wal-‘Umrah, p.59.