Celtic fans tend to sit on the Catholic side of religion, while Rangers supporters have a history that is rooted within the Protestant Community.
Those alliances see Celtic fans align themselves politically with the Republic of Ireland, with Rangers identifying strongly with Great Britain.
Games between the two sides are often fiercely fought affairs, regularly producing highly controversial moments.
Read on as we take a closer look at the rivalry.
History of the Old Firm
Celtic and Rangers were generally friendly with each other during their early years, but the situation changed dramatically in 1912.