In Arabic the word ‘Umrah is derived from al-i’timar which means a visit. Here it means paying a visit to Ka’bah, performing lawaf around it, walking between Safa and Marwah seven times, and then shaving one’s head or cutting one’s hair short.
There is consensus among scholars that it is a prescribed worship. Ibn ‘Abbas reported that the Prophet (peace be upon him) said, “An ‘Umrah in the month of Ramadan is equal (in reward) to performing a Hajj.” (This does not, however, remove from one the obligation of performing the obligatory Hajj) This was reported by Ahmad and Ibn Majah.
Abu Hurairah reported that the Prophet (peace be upon him) said, “From one ‘Umrah to the next is an atonement for any sins committed in between, and the reward for an accepted Hajj is nothing but Paradise.” This was reported by Ahmad, Bukhari and Muslim.