Hajj is the greater pilgrimage to the House of Allah in Makkah. This pillar encompasses the requirement for every financially and physically able adult Muslim to perform this pilgrimage once in their lifetime.
During the Hajj, Muslims must each wear the same simple garments and perform the same ritual acts of devotion to Allah. One of the benefits of this is that we are stripped of worldly distinction (jewelry, designer clothing, ect) and therefore reminder us that we are all equal before Allah.