In Arabic, the word ‘Umrah is derived from I‘timaar which means a visit. However, ‘Umrah in Islamic terminology, means paying a visit to Ka’bah, performing Tawaaf (circumambulation) around it, walking between Safaa and Marwah seven times. A performer of ‘Umrah puts off his Ihraam by having his hair shaved or cut. ‘Umrah can be performed along with Hajj and in other days as well.

‘Umrah can be performed during anytime in the year, there is no fixed time for ‘Umrah.

The Pillars of `Umrah are four:

a) Ihraam: which is assumed at the Meeqaat.

b) Tawaaf: around the House.

c) Sa’y: walking between As-Safaa and Al-Marwah, which consists of seven circuits.

d) Tahal-lul: which means coming out of the state of Ihraam; becoming lawful what was previously prohibited during Ihraam.

During ‘Umrah, pilgrims do not go to Minaa, ‘Arafaat and Muzdalifah or throw pebbles on the Jamrahs (stone pillars representing devils) or offer animal sacrifice. These rites are only performed during Hajj.

Source: http://www.islamweb.net/en/article/136133/how-to-perform-umrah