Use of ‘OR’ in spoken and written English

1. ‘OR’ is used to introduce an alternative.
Ex.- Do or die. / Your purse ‘OR’ your life.
2. ‘OR’ is used to mean ‘otherwise’
Ex.- We must hasten or night will overtake us.
3. ‘OR’ is used to show several Alternatives
Ex.- He may study physics or chemistry or Biology or he may enter into trade.